Exhaust Leak At Downstream Oxygen Sensor

9 liter engine is located on the exhaust pipe just behind the right exhaust manifold. Does anyone know. The converter now starts to clean the exhaust and remove the pollutants. Smoke test revealed no exhaust leaks from the manifold or any where else. The engine may have a vacuum leak, a problem in the ignition system or something similar. I used a dab of Permatex 81343 Anti-Seize Lubricant for this. Also for the O2 sensor heater element there is a battery voltage supply wire and another ground circuit for that. Replace as necessary. You will likely find one sensor in each manifold and down tube. If the data between the two sensors becomes more similar, the vehicle's computer may trigger a catalyst inefficiency check engine code, which turns on the Check Engine light. Exhaust pipe / catalytic converter leaks. In contrast to the upstream sensor, the downstream sensor should have a relatively flat waveform at approximately 0. 2 is usually the downstream O2 sensor behind the converter. You should have between. Between the first and second sensor, it may throw a CEL. Used (O2) Sensor Comparison There are also some other possibilities such as an internally leaking EGR system. A leak before the first O2 sensor can cause it to read incorrectly and and incorrectly adjust the A/F mixture. Oxygen sensors detect the amount of oxygen content in the exhaust stream and turn this information into a voltage signal that your. Inspect both exhaust manifolds and inspect the down tube extending out of the exhaust manifolds. Hooked a scan tool up and the new sensor is showing a voltage of between. 9 Volts (900 millivolts) since it did not, you can deduce correctly that it's fried and needs to be replaced. It is not CARB approved. Cruz P Matias April 8, 2018. Index-Ratio & Switch-Ratio For index-ratio and switch-ratio monitors, the converter is generally said to be degraded, if the rear-to-front switching ratio approaches about 70% (varies by application). -Exhaust Leak c - Exhaust leak is right because an exhaust system leak can cause a vehicle to have a high O2 (oxygen) reading of 3. The high or low voltage signal tells the PCM the fuel mixture is rich or lean. Supplied with a factory-fitted OE connector for easy installation. To conclude this process, use the car jack to carefully and slowly lower your vehicle. Upstream O2 is used to determine the A/F ratio of the mixture burned in the engine. Check the rear Heated O2 Sensor. If it’s not, there is a problem with either the downstream oxygen sensor or a problem with the catalytic converter. This will typically set a separate code. Modern vehicles use both an upstream and downstream oxygen sensor. The O2 sensor looks like a white spark plug and has a green wire extending out of the top of it. Check for exhaust leaks. Equip cars, trucks & SUVs with 2000 Chevrolet S10 Oxygen Sensor from AutoZone. OBD-II Trouble Codes. On all cars made after 1995, there are 2 types of oxygen sensors, what is referred to as an “upstream” and “downstream” sensor. 9 Volts (900 millivolts) since it did not, you can deduce correctly that it's fried and needs to be replaced. A good muffler shop can heat test your catalytic converter if you don't have a heat gun. For a good quality gasket you're looking at about $20 for an OEM donut gasket, 2. All you have to do is push down the little tab and pull them apart. Progress Thread 2000 Mustang Gt Poor Acceleration And Performance. In a fully functional system, the upstream oxygen sensor both controls and monitors short-term fuel trims by reacting to changes in the levels of oxygen in the exhaust stream, while the downstream sensor monitors the efficiency of the catalytic converter, and is (with a few exceptions) not directly involved in fuel trim control. My question is if there is a small exhaust leak a foot downstream of the rear O2 sensor (at most a pin hole) AND outside air was going upstream that foot to the sensor wouldn't it simply read high all the time? I am pretty sure this would be the case. You should have between. The O2 sensors are always located in the exhaust and monitor how much unburned oxygen is present in the exhaust. The Possible Causes Of Rich Codes Are:. This old of a car the downstream sensor is only used as checking device some newer cars now adjust fuel trim with A/F sensor upstream and O2 downstream and adjust fuel to keep Cat happy unlike older cars just to check the Cat. Learn How to Check an Oxygen Sensor. So, With information from the (O2) Oxygen Sensor and other sources the (ECU) can decide whether the air/fuel ratio of your engine is rich or lean. The Oxygen sensor (commonly called the O2 sensor) measures the amount of oxygen in the exhaust stream. NTK Oxygen Sensors are extensively tested during manufacturing to guarantee quality and reliability. So I'd look for the power supply to the O2 to repair that not change the O2. Check lives downstream (rear) oxygen sensor data. In contrast to the upstream sensor, the downstream sensor should have a relatively flat waveform at approximately 0. No power to o2 sensor. O2 Sensor Codes Interpretation. CASE 3: The downstream O2 sensor's wiring is melted to the exhaust pipe. The O2 sensor is mounted near the flange where the exhaust down pipe mounts to either the swing valve for turbo engines or the exhaust manifold for non-turbo or TBI engines. Buy a 2003 Mercedes ML500 Oxygen Sensor at discount prices. P1230: Open Power to Fuel Pump circuit. When the catalyst is functioning properly, the HO2S 2 is slow to respond to a large change in. 33 Heated Oxygen Sensor. The O2 sensor is mounted in the exhaust manifold to monitor how much unburned oxygen is in the exhaust as the exhaust exits the engine. Quite often P0171 is triggered in tandem with P0174, which comes on when the Bank 2 sensor detects too much oxygen in the exhaust. Oxygen sensor simulator is a racing part. To conclude this process, use the car jack to carefully and slowly lower your vehicle. Modern vehicles use both an upstream and downstream oxygen sensor. I had a bad O2 sensor code, so I replaced the sensor. 2003 Toyota Tacoma O2 Sensor Bank 1 Sensor 2. Replace the. Headers require both up- and downstream O2 sensor emulation. When an oxygen sensor is poisoned, it loses its ability to measure the oxygen content in the exhaust. The downstream O2 sensor is considered to be protected from extreme environments by the catalyst. Quite often P0171 is triggered in tandem with P0174, which comes on when the Bank 2 sensor detects too much oxygen in the exhaust. Black DOG Lila, Mar 2, 2020. Exhaust leaks. This old of a car the downstream sensor is only used as checking device some newer cars now adjust fuel trim with A/F sensor upstream and O2 downstream and adjust fuel to keep Cat happy unlike older cars just to check the Cat. Recurring Code 91 R/h O2 Sensor/exhaust Leak. Described below is a propane test which will verify your catalytic converter is bad. In some engine management configurations, downstream oxygen sensor activity is used to adjust the air/fuel operation to maintain a favorable ratio to optimize catalyst efficiency. O2 Sensor Lambda Controller Value Above Threshold due to Open Pumping Current Circuit (Bank 2 Sensor 1) P3020 O2 Sensor Signal Voltage Too Low during Coast Down Fuel Cut-Off due to Open Pumping Current Circuit (Bank 1 Sensor 1) P3021 O2 Sensor Signal Voltage Too Low during Coast Down Fuel Cut-Off due to Open Pumping Current Circuit (Bank 2. As miles accumulate, O2 sensors effectively. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING). The sensor connects to the Power Module, so install the sensor on the bank closest to where you plan to mount the Module. Corolla Timing – If your Corolla is misfiring or the exhaust timing is off, this can affect the gasses that are actually going to the O2 sensors enough to cause the P0420 code to register. Proper installation of the oxygen sensor is critical to the performance. In contrast to the upstream sensor, the downstream sensor should have a relatively flat waveform at approximately 0. When an oxygen sensor is poisoned, it loses its ability to measure the oxygen content in the exhaust. 48v while the other o2 sensor is between 0. Leaks From Oil, Antifreeze And Fuel. The WBO2 can be installed downstream of either exhaust bank. After repairing. The downstream O2 sensor is located in the exhaust path behind the catalytic converter, and is monitored for proper response to assure optimum catalytic converter efficiency. Fully tighten the oxygen sensors in place. A controller (2) performs feedback correction of an air-fuel ratio of an air-fuel mixture burnt in the engine (1) by proportional/integral control based on the output of the upstream oxygen sensor (3). If the oxygen sensor was operating normally, it would have reacted to addition of the carburetor spray immediately by producing a voltage around 0. And if it's "after the O2 sensor" I'm assuming their referring to the downpipe to midpipe connection (if they're not bullspitting you). Technician B says if the exhaust has little oxygen, the voltage of the oxygen sensor will be close to 1 volt (1000 mV) and close to zero if there is high oxygen content in the exhaust. The Oxygen sensor (commonly called the O2 sensor) measures the amount of oxygen in the exhaust stream. 3 volt (300. The high or low voltage signal tells the PCM the fuel mixture is rich or lean. Downstream oxygen sensors (located in the exhaust stream after the catalyst) are used to monitor catalytic converter efficiency. The unburned oxygen from cylinder #5 (misfire) will also add raw unburned oxygen that goes past the O2 sensor in addition to the oxygen from the vacuum/exhaust leaks. 3L Downstream O2 Oxygen Sensor: 2004-2005: And what I mean by that, is the sensor shaft that goes in the exhaust pipe is a bit smaller than. My bigger concern though are my O2 Sensors and the voltage they. Voltage produced by the O2 sensor depends on the amount of oxygen in the exhaust. The waveform reading of the upstream oxygen sensor should fluctuate. The Oxygen sensor (commonly called the O2 sensor) measures the amount of oxygen in the exhaust stream. Oxygen sensors (3, 13) are provided upstream and downstream of a three-way catalytic converter (10) in an exhaust passage (9) of an internal combustion engine (1). It osculates its current usually between -. Also I want to find out if the A/F sensors are bank specific, as there are two part numbers for the upstream sensors and also two part numbers for the downstream sensors. What would cause downstream o2 sensor voltage to be low, other than o2 sensor itself is bad? I understand that if the upstream o2 sensor voltage is high or low, it could possibly mean that the o2 sensor itself is good and the combustion got a problem. As miles accumulate, O2 sensors effectively. Possible Causes: Exhaust leak Engine mechanical problem O2 Sensor has failed O2 Sensor signal circuit or return circuit problem Fuel contamination. Note: a worn out catalytic converter can produce symptoms similar to a bad downstream O2 sensor. Downstream was tough, had to heat up exhaust pipe to get the sensor out. 9 liter engine is located on the exhaust pipe just behind the right exhaust manifold. This old of a car the downstream sensor is only used as checking device some newer cars now adjust fuel trim with A/F sensor upstream and O2 downstream and adjust fuel to keep Cat happy unlike older cars just to check the Cat. About in the middle of the voltage range Relatively high (close to 1 volt) Relatively low (close to 0 volt) Either A or B, depending on atmospheric pressure. It does this by "leaking" (recirculating) small amounts of exhaust into the intake manifold through the EGR valve. Brand new high performance downstream o2 oxygen sensor item feature: direct plug-in replacement built and tested to strict quality control standards manufactured meet or exceed oem specifications. P0136 - HO2S Sensor Circuit The downstream HO2S sensor(s)•Disconnected sensor Malfunction (HO2S-12) are continuously checked for maximum and minimum voltages. defective upstream or downstream oxygen sensor circuits a leaking exhaust fuel contaminants ignition system faults. Diagnostic Test 1. 21 volts, depending on the vehicle), the P0137 trouble code will activate. P203B P0136 [4] G3/1 (O2 sensor downstream TWC) ,: Open circuit [P0136] P203B P0136 [8] G3/1 (O2 sensor downstream TWC) ,: Sensor signal in the case of inertia fuel shutoff IMPLAUSIBLE [P0136] P203B P0137 [1] G3/1 (O2 sensor downstream TWC) ,: Short circuit to ground [P0137]. The unburned oxygen from cylinder #5 (misfire) will also add raw unburned oxygen that goes past the O2 sensor in addition to the oxygen from the vacuum/exhaust leaks. Remember, any deviation from the instructions provided for proper sensor installation will lead to inaccurate O2 readings. check wiring of O2 sensor all way back to control. Check for exhaust leaks. P0420 is caused by bad O2 sensors, failing catalytic converter, or leak in the exhaust system. 3L Downstream O2 Oxygen Sensor: 2004-2005: And what I mean by that, is the sensor shaft that goes in the exhaust pipe is a bit smaller than. P0140 code - the Downstream O2 sensor no activity diagnostic monitor is intended to diagnose Downstream O2 sensoe that is not moving or is stuck in a voltage window. EXHAUST LEAK ENGINE MECHANICAL PROBLEM 1/2 O2 SENSOR (K141) O2 SENSOR 1/2 SIGNAL CIRCUIT (K299) O2 1/2 HEATER CONTROL CIRCUIT (K904) O2 DOWNSTREAM RETURN CIRCUIT FUEL CONTAMINATION Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. See full list on autoservicecosts. Technician A says that an oxygen sensor can have one, two, three, four, or more wires, depending on the style and design. Then use an oscilliscope to check the waveforms of both upstream and downstream O2 sensors. When the catalyst is functioning properly, the HO2S 2 is slow to respond to a large change in. 1v reading from the downstream sensor. bank 1 sensor 1 - left side upstream bank 1 sensor 2 - left side downstream bank 2 sensor 1 - right side upstream. After repairing. For a good quality gasket you're looking at about $20 for an OEM donut gasket, 2. 2003 Toyota Tacoma O2 Sensor Bank 1 Sensor 2. Not sure what's going on exactly but you may have an exhaust leak or something else going on with that catalytic converter you replaced. If it's contaminated with oil (a sign that oil is leaking into the combustion chamber and being burned), the sensor tip will have dark brown deposits. Check for exhaust leaks by listening for a tapping or popping noise coming from the exhaust. Its purpose is to reduce oxides of nitrogen (NOX) pollution in the exhaust. Which technician is correct?. Although a MIL lamp may not be illuminated, there are instances when the downstream O2 sensor goal voltage is out of range, causing driveability problems or low fuel economy. The 141 and 161 problem is probably the heater circuit fuse. The sensor produces a voltage that changes when the amount of unburned oxygen in the exhaust changes. The catalyst efficiency is measured by a second oxygen sensor after the catalytic converter. P0136 - HO2S Sensor Circuit The downstream HO2S sensor(s)•Disconnected sensor Malfunction (HO2S-12) are continuously checked for maximum and minimum voltages. The converter now starts to clean the exhaust and remove the pollutants. My bigger concern though are my O2 Sensors and the voltage they. As for downstream, its the same part number for both. OBD-II Trouble Codes. Used (O2) Sensor Comparison There are also some other possibilities such as an internally leaking EGR system. The downstream oxygen sensor wiring is especially volatile since it is so far from the ECM (more distance to travel. So, Over time, your (O2) Oxygen Sensor can become caked with byproducts of combustion like sulfur, lead, fuel additives, and oil ash. The downstream O2 sensor is considered to be protected from extreme environments by the catalyst. Check the rear Heated O2 Sensor. The conditions that caused this diagnostic to fail is when the upstream O2 Sensor biased from an exhaust leak, O2 sensor contamination, or some other extreme operating condition. If you are not sure the compatibility with your car, please timely contact us via message. In fact, it would be a good idea to test each oxygen O2 sensor while you're at it. The voltage output of a zirconia oxygen sensor when the exhaust stream is lean (excess oxygen) is _____. After repairing. If exhaust oxygen content is low, such as a rich air/fuel ratio, the voltage output from the sensor may be as high as 1 volt. Inspect both exhaust manifolds and inspect the down tube extending out of the exhaust manifolds. While O2 readings alone can generally be a good indicator of lean air/fuel mixtures, it is a good idea to compare it with the other exhaust gases as well. The only other possibilities are wiring issues, and computer concerns. Repair Sensor Leak highly effective Downstream Sensors - 1pc Oxygen Sensor Spacer Repair Sensor Leak. This causes a sudden drop in the switching activity of the downstream O2 sensor, and the downstream O2 sensor's output voltage levels off to an average reading of around 0. And if it's "after the O2 sensor" I'm assuming their referring to the downpipe to midpipe connection (if they're not bullspitting you). Note: a worn out catalytic converter can produce symptoms similar to a bad downstream O2 sensor. This excess fuel in the engine can produce a sulfuric, rotten egg smell, and may even produce black smoke from the exhaust. If the PCM adds downstream short-term compensation to long-term adaptive, and a certain percentage is exceeded for 2 trips, a freeze frame is stored, the MIL illuminates and a DTC is set. Code P0133 means that there is a delay in the transmission of signals from the downstream oxygen sensor in Bank 1 to the PCM. Start with the simple things like cleaning the Mass air flow(MAF) sensor, making sure the tube from the MAF to the throttle body isn't cracked or damaged, and. 33 Heated Oxygen Sensor. To the oxygen sensor, the change to the exhaust gases in the manifold can cause inaccurate readings. The oxygen sensor transmits the data to the vehicle's PCM to maintain the optimal air to fuel ratio for your engine. The catalyst efficiency is measured by a second oxygen sensor after the catalytic converter. In contrast to the upstream sensor, the downstream sensor should have a relatively flat waveform at approximately 0. Note: a worn out catalytic converter can produce symptoms similar to a bad downstream O2 sensor. 2l downstream 1 oe 2006 ISUZU i-280 l4 2. ACTIVE DTC. P0420 is either a leak in your exhaust or a bad catusually its a bad cat. Get Yours Today! We have the best products at the right price. Check lives downstream (rear) oxygen sensor data. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING). The downstream O2 sensor is considered to be protected from extreme environments by the catalyst. The bung should be installed by a qualified exhaust technician and pressure tested. The upstream sensor is an A/F sensor and its readings look good. Technician A says that an oxygen sensor can have one, two, three, four, or more wires, depending on the style and design. upstreamoxygen sensor has to work flawlessly. What would cause downstream o2 sensor voltage to be low, other than o2 sensor itself is bad? I understand that if the upstream o2 sensor voltage is high or low, it could possibly mean that the o2 sensor itself is good and the combustion got a problem. IMPORTANT: Remember that when testing oxygen sensors the car must be warmed up. It osculates its current usually between -. I replaced the sensor with a Bosch and still had the same code. Threaded into your vehicle’s exhaust pipes or exhaust manifold is a heated oxygen sensor (HO2S), which monitors your exhaust to see if the engine is running on too much fuel and not enough air or vice versa. This cuts down the emissions as well. Then I cleared the codes and it came back. When hot (at least 600 degrees |F), the zirconium dioxide element in the sensor's tip produces a voltage signal that varies according to the difference in oxygen content between exhaust and outside air. Oxygen Sensor (OS5110) by Spectra Premium®. 3 volt (300. The downstream oxygen sensor is also known as a catalyst monitor because it indicates converter efficiency. It continuously sends signals back to the engine control computer to adjust the amount of fuel and air going into the engine cylinders. The downstream oxygen sensor wiring is especially volatile since it is so far from the ECM (more distance to travel. Now you need to grab your two new oxygen sensors and reinstall them. It is not CARB approved. 33 Heated Oxygen Sensor. P1158: Lack of Downstream Heated Oxygen Sensor Switch - Sensor Indicates Rich - Bank No. The more the downstream sensor switches in relation to the upstream sensor, the less efficient the converter is at storing and releasing oxygen. If exhaust oxygen content is low, such as a rich air/fuel ratio, the voltage output from the sensor may be as high as 1 volt. While the downstream oxygen sensor reading should be steady. The O2 sensor is mounted near the flange where the exhaust down pipe mounts to either the swing valve for turbo engines or the exhaust manifold for non-turbo or TBI engines. Then I cleared the codes and it came back. A leak in the exhaust system before the (O2) sensor will also cause incorrect readings. 5 in exhaust gasket, and 30 minutes tops of your time to replace it. Technician A says that an oxygen sensor can have one, two, three, four, or more wires, depending on the style and design. P0138 - Oxygen sensor circuit high input - downstream of P0455 - Evaporative emissions control system leak P1487 - Exhaust gas recirculation (EGR) boost. Also for the O2 sensor heater element there is a battery voltage supply wire and another ground circuit for that. Smoke test revealed no exhaust leaks from the manifold or any where else. (If it’s not too close to it). The PCM supplies a ground circuit and a reference voltage circuit of about 0. A controller (2) performs feedback correction of an air-fuel ratio of an air-fuel mixture burnt in the engine (1) by proportional/integral control based on the output of the upstream oxygen sensor (3). The sensor produces a voltage that changes when the amount of unburned oxygen in the exhaust changes. And if it's "after the O2 sensor" I'm assuming their referring to the downpipe to midpipe connection (if they're not bullspitting you). Between the first and second sensor, it may throw a CEL. May 29, 2017. The conditions that caused this diagnostic to fail is when the upstream O2 Sensor biased from an exhaust leak, O2 sensor contamination, or some other extreme operating condition. So now on to your problem. If you need help with an oxygen sensor replacement , our technicians can come to your location to install the correct the part. Technician B says that if the exhaust has little oxygen, the voltage of a conventional Nernst cell oxygen sensor will be close to 1 volt (1000 mV) and close to zero if there is high oxygen content in the exhaust. Its purpose is to reduce oxides of nitrogen (NOX) pollution in the exhaust. Comments: The bank 2 downstream. If downstream still shows lean then you are lean as both show the same trend. The downstream oxygen sensor is there only for emissions purposes. You would be able to audibly hear an exhaust leak. The sensor does not actually measure oxygen concentration, but rather the difference between the amount of oxygen in the exhaust gas and the amount of oxygen in air. Technician A says that an oxygen sensor can have one, two, three, four, or more wires, depending on the style and design. The O2 sensor’s sensing ability comes about by producing a small voltage proportionate to the exhaust oxygen content. A fault code for an O2 sensor will indicate the sensor location by sensor number (1, 2, 3 or 4) and by cylinder bank (1 or 2). Bad Catalytic Converter. 1996 and later vehicles have OBDII emissions, which means there is one O2 sensor upstream of a catalytic converter (between the engine and the cat), and one downstream of it to measure its efficiency. In Lean conditions (High in Oxygen, low fuel level) the sensor returns a low voltage because there is less differential between the oxygen in atmosphere, while in Rich conditions, (Low Oxygen, high fuel) it reads high because there is a large differential between the level of oxygen in the exhaust stream and atmosphere. P0138 - Oxygen sensor circuit high input - downstream of P0455 - Evaporative emissions control system leak P1487 - Exhaust gas recirculation (EGR) boost. Check for exhaust leaks. defective upstream or downstream oxygen sensor circuits a leaking exhaust fuel contaminants ignition system faults. so I thought. The left downstream sensor (1/2) is located in the left exhaust downpipe just after the mini-catalytic convertor, and before the main catalytic convertor 02S Sensor removal Never apply any type of grease to the oxygen sensor electrical connector, or attempt any soldering of the sensor wiring harness. One other way professionals can look for vacuum cleaner leaks is by using a smoke test. 3L Downstream O2 Oxygen Sensor: 2004-2005: And what I mean by that, is the sensor shaft that goes in the exhaust pipe is a bit smaller than. Exhaust leaks. If your engine has an oil leak, or if the engine block is damaged, the oxygen sensor can get worn out pretty quickly as the exhaust is now polluted with contaminants such as oil and engine coolant. The sensor signal eventually goes completely flat. Check for exhaust leaks before the sensor and repair as needed. Inspect both exhaust manifolds and inspect the down tube extending out of the exhaust manifolds. The downstream oxygen sensor is there only for emissions purposes. Then grab your 7/8" wrench and unscrew the sensors. Check for exhaust leaks before the sensor and repair as needed. Some DIY solutions are epoxy or putty to seal the leak. Worst of all, it can also damage the catalytic converter in the long run. This scenario assumes the cat is working properly. The downstream oxygen sensor is located directly after the catalytic converter. A leak in the exhaust system before the (O2) sensor will also cause incorrect readings. If the O2 sensor is fairly new, more diagnostics would be indicated, such as leaking coolant into the exhaust or possibly the wrong RTV sealant was used during a prior engine gasket replacement. The Possible Causes Of Rich Codes Are:. 0 is know for lean codes, but worry about that later. So, I would this post applies. •Exhaust leaks •Contaminated or damaged sensor. Start with the simple things like cleaning the Mass air flow(MAF) sensor, making sure the tube from the MAF to the throttle body isn't cracked or damaged, and. Fluctuations from the upstream oxygen sensors are normal, but the downstream oxygen sensor should report a steady voltage of around. All post-1996 vehicles have a lot of emissions equipment, including oxygen sensors. Rich mixture = High CO = Low Oxygen Weak mixture = Low CO = High Oxygen The Zirconia lambda sensor, by using precious metals, can determine the Oxygen difference between atmosphere and the exhaust gasses. Now you need to grab your two new oxygen sensors and reinstall them. O2 sensor codes that this information could be useful in diagnosing. Described below is a propane test which will verify your catalytic converter is bad. Heated oxygen sensor (HO2S), downstream - control limit reached: Wiring, HO2S-P117C: Heated oxygen sensor (HO2S) 2, bank 3 - above lean limit: Wiring, air leak, HO2S-P117D: Heated oxygen sensor (HO2S) 2, bank 3 - above rich limit: Wiring, air leak, HO2S-P117E: Heated oxygen sensor (HO2S) 2, bank 4 - above lean limit: Wiring, air leak, HO2S-P117F. Hooked a scan tool up and the new sensor is showing a voltage of between. Cruz P Matias April 8, 2018. The O2 sensor’s sensing ability comes about by producing a small voltage proportionate to the exhaust oxygen content. No other codes. When the exhaust emissions measured by the emission analyzer are too high, the car fails the emissions test. The downstream O2 sensor is considered to be protected from extreme environments by the catalyst. Learning how to check an oxygen sensor (O2) will help you confirm a potential problem with the sensor in your vehicle before you spend time and money replacing a unit that might not even need a replacement in the first place. O2 Sensor Codes Interpretation. The greater this difference, the higher the voltage it will produce, up to app 1volt. P1224: Throttle Position Sensor B out of Self-Test Range. > Exhaust pipe: any leak in the exhaust, especially before the downstream oxygen sensor will cause a false O2 sensor output. The voltage output of a zirconia oxygen sensor when the exhaust stream is lean (excess oxygen) is _____. A leaky exhaust pipe obviously can let exhaust gases out of the pipe at the leak. The computer then analyzes the readings to ensure the correct ratio of air fuel mixture for optimal fuel economy. This will cause the O2 sensor to read leaner than it should, which in turn will cause the computer to richen the fuel mixture unnecessarily and increase the fuel trim numbers. Between the first and second sensor, it may throw a CEL. It's essentially the same as code p0137, but its the second O2 sensor. Monitoring oxygen levels in the exhaust is a way of gauging the fuel mixture. If you need help with an oxygen sensor replacement , our technicians can come to your location to install the correct the part. Most often it is is either an exhaust leak, faulty cat or o2 sensor. This sensor measures the pollutants making it through the converter and out of the tailpipe. To diagnose a P0420 trouble code we begin by checking for exhaust leaks under the vehicle. So, With information from the (O2) Oxygen Sensor and other sources the (ECU) can decide whether the air/fuel ratio of your engine is rich or lean. Quite often P0171 is triggered in tandem with P0174, which comes on when the Bank 2 sensor detects too much oxygen in the exhaust. This sensor is designed to monitor oxygen in the exhaust, in order to tell your engine's control computer exactly what the air/fuel ratio is, so the computer can control the items that adjust that ratio. Bad Catalytic Converter. The sensor signal eventually goes completely flat. The sensor produces a voltage that changes when the amount of unburned oxygen in the exhaust changes. It measures the air-fuel ratio coming out of the catalytic converter to ensure the catalytic converter is functioning properly. To conclude this process, use the car jack to carefully and slowly lower your vehicle. Then I cleared the codes and it came back. A leak in the exhaust system before the (O2) sensor will also cause incorrect readings. I can see some ripples in the downstream trace that mirror the upstream sensor, which means the oxygen storage capacity of that catalyst is not as good as it should be. The Sensor's output voltage depends on the oxygen content of the exhaust stream. Brand new oxygen sensors, another new sensor for that one downstream bank 1 to ensure it wasnt faulty from the factory. The only other possibilities are wiring issues, and computer concerns. The ECU uses this output voltage t. I had a malfunctioning rear 02 sensor last year and it was a P0136 code, replaced the sensor and it went away. •Pinched, shorted, corroded wiring or pins The code will set when the voltages•Crossed sensor wires fail to meet the calibrated limits. Bank 1 Sensor 1 (Upstream) (pre-cat). Code P0133 means that there is a delay in the transmission of signals from the downstream oxygen sensor in Bank 1 to the PCM. Check for exhaust leaks, damaged wiring, or visual indications of a bad sensor. Leaky Exhaust Pipes. Learning how to check an oxygen sensor (O2) will help you confirm a potential problem with the sensor in your vehicle before you spend time and money replacing a unit that might not even need a replacement in the first place. To diagnose a P0420 trouble code we begin by checking for exhaust leaks under the vehicle. While the downstream oxygen sensor reading should be steady. Index-Ratio & Switch-Ratio For index-ratio and switch-ratio monitors, the converter is generally said to be degraded, if the rear-to-front switching ratio approaches about 70% (varies by application). Downstream oxygen sensors (located in the exhaust stream after the catalyst) are used to monitor catalytic converter efficiency. Also I want to find out if the A/F sensors are bank specific, as there are two part numbers for the upstream sensors and also two part numbers for the downstream sensors. Then try to run the car, and see if there is still a bad reading on the oxygen sensor. If it’s not, there is a problem with either the downstream oxygen sensor or a problem with the catalytic converter. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING). What would cause downstream o2 sensor voltage to be low, other than o2 sensor itself is bad? I understand that if the upstream o2 sensor voltage is high or low, it could possibly mean that the o2 sensor itself is good and the combustion got a problem. It is used to determine the concentration of oxygen in the exhaust gas. No combination of exhaust leaks can duplicate downstream and upstream sinusoidal oxygen sensor readings. Check the catalytic converter, replace if necessary. This is the only sensor that makes its own voltage. An exhaust leak near the upstream sensor can cause the downstream sensor to read a steady lean condition. In that case, your OBDII scanner should be reading a lean 0. Described below is a propane test which will verify your catalytic converter is bad. It osculates its current usually between -. 25) Technician A says that oxygen sensors can have one, two, three, four, or more wires, depending on the style and design. Precision-manufactured with a sensing element incorporating premier technical ceramics Optimizes emissions and fuel economy when replacing worn oxygen sensors. Its purpose is to reduce oxides of nitrogen (NOX) pollution in the exhaust. So, Over time, your (O2) Oxygen Sensor can become caked with byproducts of combustion like sulfur, lead, fuel additives, and oil ash. The conditions that caused this diagnostic to fail is when the upstream O2 Sensor biased from an exhaust leak, O2 sensor contamination, or some other extreme operating condition. Comments: The bank 2 downstream. 4 at idle and it doesn’t really get to crazy but the downstream O2 sensor just seems funny to me. Also I want to find out if the A/F sensors are bank specific, as there are two part numbers for the upstream sensors and also two part numbers for the downstream sensors. Does anyone know. •Pinched, shorted, corroded wiring or pins The code will set when the voltages•Crossed sensor wires fail to meet the calibrated limits. Scroll through this page and find out about the variants, how they work, test methods, and important information on the correct replacement of lambda sensors. Buy a 1995 Chevrolet S10 Oxygen Sensor at discount prices. Next step is to measure the voltage at the oxygen sensor on Bank 2. P1158: Lack of Downstream Heated Oxygen Sensor Switch - Sensor Indicates Rich - Bank No. When the exhaust emissions measured by the emission analyzer are too high, the car fails the emissions test. I am sure i'm going to have to replace a my cat as i had previously had misfires that have now been solved. Check for exhaust leaks before the sensor and repair as needed. Proper installation of the oxygen sensor is critical to the performance. So, With information from the (O2) Oxygen Sensor and other sources the (ECU) can decide whether the air/fuel ratio of your engine is rich or lean. This cuts down the emissions as well. No other codes. I just had this replaced this time last year. To understand why an exhaust leak is so detrimental to O2 sensor (also known as a wideband sensor) performance, one must first understand how an O2 sensor works. The O2 sensor’s sensing ability comes about by producing a small voltage proportionate to the exhaust oxygen content. If it's too tight a fit and you can't get a wrench on them, the special O2 sensors socket might be a better choice here. P0167 O2 Sensor Heater Circuit Malfunction (Bank 2 Sensor 3) P0170 Fuel Trim Malfunction (Bank 1) ) check vaccum leaks first or P0171 System too Lean (Bank 1) ) faulty air mass flow sensor. Oxygen sensors detect the amount of oxygen content in the exhaust stream and turn this information into a voltage signal that your. The downstream O2 sensor is the sensor used for catalyst efficiency. Check sensor voltage after the vehicle has fully warmed up. When an oxygen sensor is poisoned, it loses its ability to measure the oxygen content in the exhaust. If a bad oxygen sensor disrupts the air to fuel ratio mixture, or too much fuel is injected into the engine, your vehicle's gas mileage will be reduced. NARROW-RANGE SENSORS. Anytime Exhaust can leak out of the system before crossing the O2 sensor you lose some signaling power at the sensor, corresponding to this, air may be sucked into the exhaust system between exhaust pulses due to negative pressure, further contaminating the reading. 9 Volts (900 millivolts) since it did not, you can deduce correctly that it's fried and needs to be replaced. so I thought. A leaking exhaust could cause the P0420 but the leak would have to be between the TWC and the exhaust manifold. P2280 Air leak/blockage between air filter and MAF sensor P2281 Air leak between MAF sensor and throttle body P2415 Oxygen sensor 1, bank 2 - exhaust sample error. Not sure what's going on exactly but you may have an exhaust leak or something else going on with that catalytic converter you replaced. P1158: Lack of Downstream Heated Oxygen Sensor Switch - Sensor Indicates Rich - Bank No. The O2 sensor is mounted in the exhaust manifold to monitor how much unburned oxygen is in the exhaust as the exhaust exits the engine. In that case, your OBDII scanner should be reading a lean 0. This produces a low voltage, below. You will likely find one sensor in each manifold and down tube. One of the prime reasons for this could be a faulty oxygen sensor. It tells the computer if the fuel mixture is burning rich (less oxygen) or lean (more oxygen). I swapped the downstream sensors and the code went to the other side. The locations have been given numbers and will be used in the accompanying charts to identify the positions of O2sensors in most vehicles. Oxygen sensor simulator is a racing part. The upstream oxygen sensor was replaced three times (twice with after market sensors from the car parts store and one from the dealership), the downstream sensor was replaced twice, the wires were cleaned out, the flex pipe was replaced, seafoam engine cleaner was added, premium gas was used for two cycles. Pypes X-pipe Exhaust Leak? Jan 1, 2017. I have installed new Motorcraft O2 sensors and get the same codes. It is not CARB approved. When an oxygen sensor is poisoned, it loses its ability to measure the oxygen content in the exhaust. I used a dab of Permatex 81343 Anti-Seize Lubricant for this. You should have between. Then grab your 7/8" wrench and unscrew the sensors. Headers require both up- and downstream O2 sensor emulation. This scenario assumes the cat is working properly. P0167 O2 Sensor Heater Circuit Malfunction (Bank 2 Sensor 3) P0170 Fuel Trim Malfunction (Bank 1) ) check vaccum leaks first or P0171 System too Lean (Bank 1) ) faulty air mass flow sensor. If you need help with an oxygen sensor replacement , our technicians can come to your location to install the correct the part. Slow signal of precat exhaust o2 sensor may prevent the downstream oxygen sensor emulator from working. 9 Volts (900 millivolts) since it did not, you can deduce correctly that it's fried and needs to be replaced. Step 1 - Apply penetrating oil to the O2 sensor and let it soak Locate the faulty O2 sensor which should be positioned in the exhaust manifold just before or just after the catalytic converter. A controller (2) performs feedback correction of an air-fuel ratio of an air-fuel mixture burnt in the engine (1) by proportional/integral control based on the output of the upstream oxygen sensor (3). Buy a 1995 Chevrolet S10 Oxygen Sensor at discount prices. Position: Downstream Driver Side. A good muffler shop can heat test your catalytic converter if you don't have a heat gun. The computer does a simple calculation (upstream O2 value ? downstream O2 value). 0 Swap: 1979 - 1995 (Fox, SN95. O2 Sensor Lambda Controller Value Above Threshold due to Open Pumping Current Circuit (Bank 2 Sensor 1) P3020 O2 Sensor Signal Voltage Too Low during Coast Down Fuel Cut-Off due to Open Pumping Current Circuit (Bank 1 Sensor 1) P3021 O2 Sensor Signal Voltage Too Low during Coast Down Fuel Cut-Off due to Open Pumping Current Circuit (Bank 2. Exhaust leaks. If the remaining oxygen content is less than 3 % (rich mixture), the sensor voltage rises to 0. The downstream O2 sensor is the sensor used for catalyst efficiency. The downstream oxygen sensor voltage reading should be steady. •An oxygen sensor is not reading (functioning) properly •There is an exhaust leak First, inspect for exhaust leaks. The only other possibilities are wiring issues, and computer concerns. The sensor connects to the Power Module, so install the sensor on the bank closest to where you plan to mount the Module. To diagnose a P0420 trouble code we begin by checking for exhaust leaks under the vehicle. Once you have located the faulty sensor, drench it in penetrating oil, allowing it to soak for at least 24 hours prior to performing the task. This cuts down the emissions as well. Some DIY solutions are epoxy or putty to seal the leak. Supplied with a factory-fitted OE connector for easy installation. Described below is a propane test which will verify your catalytic converter is bad. In some circumstances, the catalytic converter may need to be replaced. Exhaust leaks. It osculates its current usually between -. An upstream O-2 sensor is located before the catalytic (CAT) converter, while a downstream O-2 sensor is located past the CAT. Code P0133 means that there is a delay in the transmission of signals from the downstream oxygen sensor in Bank 1 to the PCM. It tells the computer if the fuel mixture is burning rich (less oxygen) or lean (more oxygen). Does this sound like a lean condition from a bad oxygen sensor or a rich condition from an exhaust leak? It seems to me like a sensor is switching too slow, causing the mixture to stay lean too long, but on the other hand, I do have wet plugs and a suspicious tick and get a faint whiff of exhaust off the passenger manifold. I have installed new Motorcraft O2 sensors and get the same codes. -Exhaust Leak c - Exhaust leak is right because an exhaust system leak can cause a vehicle to have a high O2 (oxygen) reading of 3. (downstream. If you need help with an oxygen sensor replacement , our technicians can come to your location to install the correct the part. On some exhaust manifolds that have a connected catalytic converter, cracks can occur at the flange that might connect to the downstream catalytic converter. It oxidizes (burns) any residual fuel vapors (unburned hydrocarbons or HC) in the exhaust. Start with the simple things like cleaning the Mass air flow(MAF) sensor, making sure the tube from the MAF to the throttle body isn't cracked or damaged, and. Your exhaust is constantly heating up and cooling down and more than likely there has been some corrosion between your exhaust and O2 sensor. This Oxygen Storage Capacity (OSC) is a measurement of the catalyst's ability to control emissions. Check wire harness or connector (oxygen sensor - EFI relay): I am stuck here also. • The oxygen sensor should be located between 12” and 48” from the engine • Ensure there are no leaks in the exhaust system, as this will create an artificially lean (higher) AFR reading • Turbocharged applications, it is recommended that the sensor be installed downstream of the turbine. The exhaust of a gasoline Powered engine typically contains up to 2% oxygen. The downstream O2 sensor is considered to be protected from extreme environments by the catalyst. ACTIVE DTC. Look for a vacuum leak around the intake. P0420 is either a leak in your exhaust or a bad catusually its a bad cat. No power to o2 sensor. For example HO2S11 would be the oxygen sensor on bank 1 and first in line (pre catalytic converter) and HO2S12 would be on bank 1, but second in line (the monitor) An oxygen sensor creates a voltage between 0 and 1 volt by means of a chemical reaction between the sensor element and the oxygen in the exhaust passing across that element. 48v while the other o2 sensor is between 0. The downstream oxygen sensor wiring is especially volatile since it is so far from the ECM (more distance to travel. Make sense? _____. By analyzing the waveforms of operation of the lambda sensor in different modes of engine operation, functioning of the sensor itself can be assessed as well as the functioning of the engine management system on the whole. My bigger concern though are my O2 Sensors and the voltage they. This will cause the O2 sensor to read leaner than it should, which in turn will cause the computer to richen the fuel mixture unnecessarily and increase the fuel trim numbers. The engine management knows when not to trust a contaminated oxygen sensor. This is the only sensor that makes its own voltage. so I thought. I purchased the 4L3Z-9G444-AA (DY-992) and it was an exact fit for my 2007 F-150 STX 4x4 downstream oxygen sensor. 3L) -General/Talk-7: Jun 1, 2016: T: Engine. Remember, any deviation from the instructions provided for proper sensor installation will lead to inaccurate O2 readings. For a good quality gasket you're looking at about $20 for an OEM donut gasket, 2. A leak in the exhaust system before the (O2) sensor will also cause incorrect readings. The sensor produces a voltage that changes when the amount of unburned oxygen in the exhaust changes. This causes a sudden drop in the switching activity of the downstream O2 sensor, and the downstream O2 sensor's output voltage levels off to an average reading of around 0. If the remaining oxygen content is less than 3 % (rich mixture), the sensor voltage rises to 0. You will likely find one sensor in each manifold and down tube. Also I want to find out if the A/F sensors are bank specific, as there are two part numbers for the upstream sensors and also two part numbers for the downstream sensors. Bank 1 Sensor 1 (Upstream) (pre-cat). Add widgets in Appearance > Widgets > Off-Canvas Sidebar. The second sensor is usually further away from the engine down the exhaust system, but still close to the engine. What would cause downstream o2 sensor voltage to be low, other than o2 sensor itself is bad? I understand that if the upstream o2 sensor voltage is high or low, it could possibly mean that the o2 sensor itself is good and the combustion got a problem. Its purpose is to reduce oxides of nitrogen (NOX) pollution in the exhaust. If you need help with an oxygen sensor replacement , our technicians can come to your location to install the correct the part. Check for exhaust leaks before the sensor and repair as needed. When functioning correctly and the vehicle is running in a closed-loop mode. 1v reading from the downstream sensor. It is not the one in the manifold but the one after the converter. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING). Also I want to find out if the A/F sensors are bank specific, as there are two part numbers for the upstream sensors and also two part numbers for the downstream sensors. Headers require both up- and downstream O2 sensor emulation. The catalytic converter has oxygen (O 2) sensors in the front and behind. Buy a 1995 Chevrolet S10 Oxygen Sensor at discount prices. As I said earlier, the downstream sensor is more to fine tune the exhaust gases downstream. 1996 and later vehicles have OBDII emissions, which means there is one O2 sensor upstream of a catalytic converter (between the engine and the cat), and one downstream of it to measure its efficiency. The downstream oxygen sensor wiring is especially volatile since it is so far from the ECM (more distance to travel. The plug fouling may have started from an over-rich mixture. Anytime Exhaust can leak out of the system before crossing the O2 sensor you lose some signaling power at the sensor, corresponding to this, air may be sucked into the exhaust system between exhaust pulses due to negative pressure, further contaminating the reading. 48v while the other o2 sensor is between 0. Oxygen sensor simulator is a racing part. If downstream still shows lean then you are lean as both show the same trend. A bad or failing oxygen sensor will have a negative impact on environmental emissions and engine performance, so there are a 3 things to watch out for before your oxygen sensor completely fails. check wiring of O2 sensor all way back to control. Code P0133 means that there is a delay in the transmission of signals from the downstream oxygen sensor in Bank 1 to the PCM. Be sure you check the sensor, wiring harness, connectors, catalytic converter, and inspect for exhaust leaks. Corolla Timing – If your Corolla is misfiring or the exhaust timing is off, this can affect the gasses that are actually going to the O2 sensors enough to cause the P0420 code to register. 0 Swap: 1979 - 1995 (Fox, SN95. Not sure what's going on exactly but you may have an exhaust leak or something else going on with that catalytic converter you replaced. In some engine management configurations, downstream oxygen sensor activity is used to adjust the air/fuel operation to maintain a favorable ratio to optimize catalyst efficiency. The ECU uses this output voltage t. The O2 sensor measures the oxygen content of the exhaust. To understand why an exhaust leak is so detrimental to O2 sensor (also known as a wideband sensor) performance, one must first understand how an O2 sensor works. Also for the O2 sensor heater element there is a battery voltage supply wire and another ground circuit for that. (If it’s not too close to it). Oxygen sensor readings may be administered with a scan device while checking for leaks with propane, by shopping for increased readings when enriching the blend. Inspect both exhaust manifolds and inspect the down tube extending out of the exhaust manifolds. If that leak is upstream of the sensor, it will see the extra oxygen and set a trouble code. One other way professionals can look for vacuum cleaner leaks is by using a smoke test. So now for the code. This produces a low voltage, below. As miles accumulate, O2 sensors effectively. Leaky Exhaust Pipes. Part number 13280 O2 sensor is for Cali-emissions and won't fit your upstream. 5% with normal HC and CO readings (HC = 90 ppm and CO = 0. You will likely find one sensor in each manifold and down tube. If it's too tight a fit and you can't get a wrench on them, the special O2 sensors socket might be a better choice here. After repairing. 8L Up/Downstream 2002 2001 1999 1998. The O2 sensor’s sensing ability comes about by producing a small voltage proportionate to the exhaust oxygen content. IMPORTANT: Remember that when testing oxygen sensors the car must be warmed up. A leak in the exhaust system before the (O2) sensor will also cause incorrect readings. This scenario assumes the cat is working properly. It started with a CEL that said insufficient activity for Bank 1 Sensor 2 o2 sensor. These sensors are broken down into two categories, upstream and downstream. So I'd look for the power supply to the O2 to repair that not change the O2. Slow signal of precat exhaust o2 sensor may prevent the downstream oxygen sensor emulator from working. A bad or failing oxygen sensor will have a negative impact on environmental emissions and engine performance, so there are a 3 things to watch out for before your oxygen sensor completely fails. So, Over time, your (O2) Oxygen Sensor can become caked with byproducts of combustion like sulfur, lead, fuel additives, and oil ash. 0L O2 Mitsubishi fit Sensor Oxygen 02-05, 02-05 Oxygen Sensor Upstream O2 Mitsubishi 2. This is a costly repair, but common with a p0420 code. Oxygen sensors detect the amount of oxygen content in the exhaust stream and turn this information into a voltage signal that your. Sensor 2 is the sensor that is located after (downstream) the catalytic converter or also called the post-cat. Get Yours Today! We have the best products at the right price. The PCM supplies a ground circuit and a reference voltage circuit of about 0. Described below is a propane test which will verify your catalytic converter is bad. Index-Ratio & Switch-Ratio For index-ratio and switch-ratio monitors, the converter is generally said to be degraded, if the rear-to-front switching ratio approaches about 70% (varies by application). I’m having some troubles with both O2 sensors (P0141, P0161 and P0156). An exhaust leak near the upstream sensor can cause the downstream sensor to read a steady lean condition. Supplied with a factory-fitted OE connector for easy installation. CASE 3: The downstream O2 sensor's wiring is melted to the exhaust pipe. The plug fouling may have started from an over-rich mixture. The most common way or repairing is the replacement of the indicated oxygen sensor (bank 2 sensor 2) If there are any leaks in the exhaust, then they must be repaired before any oxygen sensor is replaced; It is not uncommon to find damaged wiring in the oxygen sensor circuit that would need to be repaired. So now on to your problem. Fluctuations from the upstream oxygen sensors are normal, but the downstream oxygen sensor should report a steady voltage of around. Technician B says that if the exhaust has little oxygen, the voltage of a conventional Nernst cell oxygen sensor will be close to 1 volt (1000 mV) and close to zero if there is high oxygen content in the exhaust. Your exhaust is constantly heating up and cooling down and more than likely there has been some corrosion between your exhaust and O2 sensor. Isuzu Ascender V8 5. Add widgets in Appearance > Widgets > Off-Canvas Sidebar. Make sure there are no exhaust leaks between the engine and the O2 sensor. The plug fouling may have started from an over-rich mixture. The downstream oxygen sensor monitors the catalytic converter. P0420 is caused by bad O2 sensors, failing catalytic converter, or leak in the exhaust system. If you need help with an oxygen sensor replacement , our technicians can come to your location to install the correct the part. No other codes. If downstream still shows lean then you are lean as both show the same trend. This is for my ‘02 Mustang GT. The locations have been given numbers and will be used in the accompanying charts to identify the positions of O2sensors in most vehicles. If it’s not, there is a problem with either the downstream oxygen sensor or a problem with the catalytic converter. Both O2 sensor measures how much O2 is present in the exhaust stream. In contrast to the upstream sensor, the downstream sensor should have a relatively flat waveform at approximately 0. 9 V in proportion to the increased difference. Mechanic's Assistant: Have you located all of the vehicle's oxygen sensors? Are the wires leading to and from each intact and in. 3 volt (300. A bad or failing oxygen sensor will have a negative impact on environmental emissions and engine performance, so there are a 3 things to watch out for before your oxygen sensor completely fails. Black DOG Lila, Mar 2, 2020. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING). This old of a car the downstream sensor is only used as checking device some newer cars now adjust fuel trim with A/F sensor upstream and O2 downstream and adjust fuel to keep Cat happy unlike older cars just to check the Cat. It is not CARB approved. Upstream Downstream & NEW Lancer 2. 0L Downstream fit NEW & Lancer. Make sure you use anti seize compound on the studs used to bolt this sensor to the exhaust pipe and torque it down good to prevent air leaks. Not sure what's going on exactly but you may have an exhaust leak or something else going on with that catalytic converter you replaced. CASE 3: The downstream O2 sensor's wiring is melted to the exhaust pipe. The ECU uses this output voltage t. The waveform reading of the upstream oxygen sensor should fluctuate. -Exhaust Leak c - Exhaust leak is right because an exhaust system leak can cause a vehicle to have a high O2 (oxygen) reading of 3. It started with a CEL that said insufficient activity for Bank 1 Sensor 2 o2 sensor. Position: Downstream Driver Side. It tells the controllers if the downstream exhaust gases are running lean/rich in addition to the inputs provided by the upstream sensor for different engine operating points. Threaded into your vehicle’s exhaust pipes or exhaust manifold is a heated oxygen sensor (HO2S), which monitors your exhaust to see if the engine is running on too much fuel and not enough air or vice versa. P0136 - HO2S Sensor Circuit The downstream HO2S sensor(s)•Disconnected sensor Malfunction (HO2S-12) are continuously checked for maximum and minimum voltages. The downstream O2 sensor is the sensor used for catalyst efficiency. 1 is usually the one in the exhaust manifold, while sensor No. 0 is know for lean codes, but worry about that later. bank 1 sensor 1 - left side upstream bank 1 sensor 2 - left side downstream bank 2 sensor 1 - right side upstream. The unburned oxygen from cylinder #5 (misfire) will also add raw unburned oxygen that goes past the O2 sensor in addition to the oxygen from the vacuum/exhaust leaks. So now on to your problem. Also I want to find out if the A/F sensors are bank specific, as there are two part numbers for the upstream sensors and also two part numbers for the downstream sensors. According to Wikipedia, the catalytic converter is “an emissions control device that converts toxic gases and pollutants in exhaust. The later OBD2 setups 96+ had the post-cat/ downstream O2 sensor only to monitor the performance of the catalytic convertor. The computer evaluates and compares signals from the upstream and downstream sensors to assess whether the cat. Start with the simple things like cleaning the Mass air flow(MAF) sensor, making sure the tube from the MAF to the throttle body isn't cracked or damaged, and. This demand causes a voltage to build up, due to transportation of oxygen ions through the sensor layer. EXHAUST LEAK ENGINE MECHANICAL PROBLEM 1/2 O2 SENSOR (K141) O2 SENSOR 1/2 SIGNAL CIRCUIT (K299) O2 1/2 HEATER CONTROL CIRCUIT (K904) O2 DOWNSTREAM RETURN CIRCUIT FUEL CONTAMINATION Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. If you have an exhaust leak behind the rear O2 sensor, it should not cause the code. It is not the one in the manifold but the one after the converter. The oxygen sensor is a heat-activated sensor downstream in the exhaust system that monitors the air/fuel ratio via a chemical reaction with the exhaust gasses. After repairing. (If it’s not too close to it). Your exhaust is constantly heating up and cooling down and more than likely there has been some corrosion between your exhaust and O2 sensor. So, I would this post applies. A P0142 code refers to the Bank 1 O2, 3 sensor or the 3rd downstream (post-cat) O2 sensor on Bank 1, it is a four wire sensor. Once the oxygen sensors have been wiped dry, use your wrench to insert them back in the exhaust manifold (s) and the other locations from which you originally removed them. P203B P0136 [4] G3/1 (O2 sensor downstream TWC) ,: Open circuit [P0136] P203B P0136 [8] G3/1 (O2 sensor downstream TWC) ,: Sensor signal in the case of inertia fuel shutoff IMPLAUSIBLE [P0136] P203B P0137 [1] G3/1 (O2 sensor downstream TWC) ,: Short circuit to ground [P0137]. Check for exhaust leaks upstream of the O2 sensors before assuming it's the catalytic converter.