Exhaust Leak At Downstream Oxygen Sensor

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. There are pics included. There are two oxygen sensors: one is upstream of the catalytic converter and one downstream of the catalytic converter. I am willing to weld it up but really don't want to weld it to find out it's not my problem. The downstream O2 Sensor is located in the exhaust path behind the catalytic converter, is monitored for proper response to assure optimum catalytic converter efficiency. 7 parts air for each 1 part fuel). A General Motors vehicle is being checked using mode $06 for the proper operation of the oxygen sensor. Check for leaks as far a 2 feet behind the Downstream O2 sesnsors. Rather than quickly paying for a replacement, talk to a local shop about doing more in depth exhaust diagnostics to figure out if it really time to retire an oxygen sensor that is not performing correctly. 5 in exhaust gasket, and 30 minutes tops of your time to replace it. The only other possibilities are wiring issues, and computer concerns. Anyway I was thinking since the O2 sensor is after the exhaust leak could the leak be sucking air in causing the O2 sensor to think the engine is running lean and than tell the ECU to make it run richer? 94 pathfinder by the way Thanks. The oxygen sensor is mounted in the exhaust manifold. I already replaced the bank 2 cat with the used one I had purchased, due to lack of power under load, the downstream o2 sensor was almost identical to the upstream, and the CEL for P0430. I took it to a muffler shop and they said they found a crack somewhere in my exhaust and welded it. Take note of the oxygen sensor plugs on the top of the fuel rail cover. The upstream O2 sensor in the exhaust manifold reflects the condition of the exhaust gases as they exit the engine. 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. This scenario assumes the cat is working properly. Finally, the other most common issue is an exhaust leak. That's the answer then. A rear or downstream oxygen sensor is installed in the exhaust after the catalytic converter. Sensor 2 is Downstream, after the converter. Dealer wants over $300 to replace and says if the sensor is not replaced, damage will occur to catalytic converters. Air leaks can be either on the intake side or exhaust side of the engine. Key-dance revealed P0157 - Bank 2 Sensor 2 driver downstream had a low voltage condition. The downstream O2 sensor on the other hand, is found behind the catalytic converter, and its job is to check the efficiency of the converter by checking the O2 content of the exhaust right after it leaves the converter. Check the rear Heated O2 Sensor. The oxygen sensor is an important part of a car engine. The P2270 DTC refers to downstream sensor (after the catalytic converter), sensor #2 on bank #1. Possible Causes EXHAUST LEAK (K141) O2 1/2 SIGNAL CIRCUIT (K904) O2 RETURN DOWNSTREAM CIRCUIT 1/2 O2 SENSOR. This is called the catalyst's "light off" temperature. Who is correct?. The middle oxygen sensor bung is used for an extra oxygen sensor if you install an air/fuel ratio gauge later. Could this exhuast leak cause me to get bad readings?. The downstream O2 sensor in or behind the catalytic converter reflects the condition. and for shits and giggles i also replaced the downstream one as well. leak in the exhaust, usually at the outlet to the en gine converter. The converter now starts to clean the exhaust and remove the pollutants. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING). Simply screw between lambda boss and lambda sensor. After the repairs have been made, verify proper O2 sensor operation. 4 mm (6 inches) behind the downstream O2 sensor - O2 sensor seal points - O2 sensor boss welds - Flange/joint connection(s) - Exhaust manifold to cylinder head connection(s) - EGR solenoid gasket. P2A00 code definition. Along with an upgraded exhaust manifold, improved oxygen sensors also keep your emissions within a normal range. Modern fuel control systems use the downstream sensor as part of the fuel control system and to serve as a default sensor if the upstream sensor fails. The O2 sensors are always located in the exhaust and monitor how much unburned oxygen is present in the exhaust. After years of service, an oxygen (O2) sensor tends to firmly stick to the exhaust pipe or. For the first two times, I simply changed the O2 sensor. Bank #1 is the side of the engine that contains cylinder #1. O2 sensor There are also some other possibilities such as an internally leaking EGR system. 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. check for any exhaust leaks. RockAuto ships auto parts and body parts from over 300 manufacturers to customers' doors worldwide, all at warehouse prices. two of them on the exhaust pipes (left and right) and one after the cat. On 1996 and newer vehicles with OBDII, a downstream oxygen sensor monitors the efficiency of the converter and triggers the Check Engine light if the converter is not doing its job. Now O2 sensor Sensor 2 is a sin wave from 0. Check the rear Heated O2 Sensor. How to Test Trouble Code P0420 (GM 3. The A/F heater circuit is 4 ohms, specs say around 2 ohms. The downstream oxygen sensor should find a reading near center (about. It also runs between 40 and. 045V if the catalytic converter is working properly. There are pics included. The Possible Causes Of Rich Codes Are:. An engine misfire, leaky exhaust valve or a leak in the exhaust manifold gasket that allows air into the exhaust may also cause this type of code to be set. Otherwise the intake manifold gaskets are probably leaking. Be sure to confirm the issue isn't related to exhaust leaks, the exhaust gas recirculation (EGR) system, vacuum leaks, the MAF sensor, etc prior to replacing the O2 sensor. It may be worth nothing that this just started a few days ago, before I changed the O2 sensor. Usually found on the exhaust manifold, your oxygen sensor passes oxygen levels present in the car or truck's exhaust system to the computer. I just replaced the CATALYTIC CONVERTER but the scanner STILL shows a P0420 code. ACTIVE DTC. I can physically touch it with my fingers but getting my tools in there to extract it is impossible. 48v while the other o2 sensor is between 0 and. 9V across grey/black wires. I located the sensor but don't know how to get. ACTIVE DTC. These sensors are broken down into two categories, upstream and downstream. Most emission-controlled cars have two to four oxygen sensors, depending on the amount of cylinders and exhaust pattern. What does that mean? Basically this means that an oxygen sensor in bank 1 has detected a lean condition (too much oxygen in the exhaust). I had a mechanic run it on their code reader and told me that the truck (96 f-150 2wd 4. Could this exhuast leak cause me to get bad readings?. I first checked and ruled out vacuum leaks, exhaust leaks, and no misfire readings on all cylinders. For a complete wiring diagram Refer to Section 8W. The typical signs of a faulty oxygen sensor include increased exhaust emissions due to poor air fuel mixture, engine hesitations, engine misfires, stalling, rough idling and increased fuel consumption. When the oxygen content is lower, caused by a rich condition, the O2 sensor produces a higher voltage, above 450 mV. i have a third plug near the 02 connectors but unlike the o2. The O2 sensors are always located in the exhaust and monitor how much unburned oxygen is present in the exhaust. How Does An O2 Sensor Work 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. It is especially volatile since it is right next to the hot exhaust at all times. On V6/V8/V10 engines, Bank 1 is the side of the engine that has cylinder #1. Oxygen Sensor Malfunction The oxygen sensor is a heat-activated sensor downstream in the exhaust system that monitors the air. Is there a gasket between the bracket and o2 sensor? I dont know if I should replace the part of pipe or just replace the gasket, if there is any. From what i know a p0171 is usually a bad or dirty maf, a vacuum leak bad, o2 sensor, exhaust leak, or clogged fuel filter. A front oxygen sensor is installed in the exhaust manifold or in the front exhaust pipe before the catalytic converter. A wideband sensor works by. When Monitored: The monitor will run at between 1400 and 2300 RPM. 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 front reading should vary, the rear should be steady. Does this exhaust leak cause any issues? Logic tells me since it is downstream of the front O2 sensors it shouldnt have an impact but I just want to check with others here. Replied by barneyb on topic Exhaust Leak Idle Issue The oxygen sensor compares the amount of oxygen in the exhaust to the amount in the ambient air outside the exhaust. After the repairs have been made, verify proper O2 sensor operation. ?Check for exhaust leaks at the manifold, pipes, catalytic converter. To diagnose a P0420 trouble code we begin by checking for exhaust leaks under the vehicle. The oxygen sensor downstream of the catalytic converter is called a catalyst monitor and monitors the efficiency of the catalytic converter Check for exhaust leaks, test oxygen sensor. You can either replace them (new or junk yard), look for headers, or get them fixed (brazed or Lock-N-Stitch technique). No way I was going to the dealer. Oxygen sensors detect the amount of oxygen content in the exhaust stream. Denso Oxygen Sensor is designed to detect the amount of oxygen in the exhaust stream. The downstream oxygen sensor is there only for emissions purposes. Once establishing how far downstream in the exhaust system to position the wideband O2 sensor, the bung should be mounted between 9 o’clock and 3 o’clock. O2 downstream sensor code & leaks. long periods of idle time can render a non-heated or older o2 sensor too cold for it to function at all. Remove the upstream and downstream O2 sensor connectors: this is optional, but depending on your vehicle it may be a good idea to keep the sensor wiring safe from an accidental burn. What does that mean? Basically this means that an oxygen sensor in bank 1 has detected a lean condition (too much oxygen in the exhaust). The waveform of the sensor behind the converter should be more steady). Without a scope/DSM/scan tool to see the signal in real time, it is hard to say whether to sensor is working well or not. If the converter is working at high efficiency, the downstream O2 sensor signal will be almost flat and show very little switching activity compared to the upstream O2 sensor(s). Headers require both up- and downstream O2 Sensor elimination. The code I was getting meant: Oxygen Sensor Circuit Slow Response (Bank 1, Sensor 1). All O2 sensors are vented to the atmosphere which contains Approximately 21% oxygen. I am willing to weld it up but really don't want to weld it to find out it's not my problem. It is my hope that this short oxygen sensor article will open your mind on the subject. 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 downstream oxygen sensor needs to have the wiring removed from the clip holding it in place, and then pulled out to install in the J hook style bung way at the bottom of the downpipe. Your BMW’s or MINI’s oxygen (O2) sensor is like the traffic cop at a busy intersection. I found a exhaust leak around the downstream o2 sensor, where the O2 sitting in bracket. No way I was going to the dealer. 3V but should be above 0. A leaky exhaust pipe obviously can let exhaust gases out of the pipe at the leak. The O2 sensors are always located in the exhaust and monitor how much unburned oxygen is present in the exhaust. This is the third time I've had both that code, and the P0133 code which indicates bank 1 sensor 1. Denso Oxygen Sensor is designed to detect the amount of oxygen in the exhaust stream. I had an exhaust leak up front on the pipe with the downstream O2 sensor that was repaired and all was well for a few weeks. Next, unscrew the bolts at the back of the converter, followed by the ones at the front, and remove it from the car. So, I would this post applies. Does that suggest a weak O2 sensor needing replacement?. It would be a good idea to check the exhaust for leaks first. You would be able to audibly hear an exhaust leak. What is claimed: 1. The Bosch oxygen sensor utilizes a mix of zirconium and yttrium oxides and other elements to form a tough base that withstands the intense stress to which oxygen sensors are subjected. A rear or downstream oxygen sensor is installed in the exhaust after the catalytic converter. If you know how to change an oxygen sensor on your 2000 Dodge Stratus, you not only save money in car repairs but avoid a much more expensive repair. The O2 sensor is mounted in the exhaust stream, usually with one sensor not far from the exhaust manifold and one farther down after the catalytic converter. A General Motors vehicle is being checked using mode $06 for the proper operation of the oxygen sensor. But air can also be sucked into the pipe at the same leak. 2 is usually the downstream O2 sensor behind the converter. The downstream oxygen sensor needs to have the wiring removed from the clip holding it in place, and then pulled out to install in the J hook style bung way at the bottom of the downpipe. This month, we’re moving downstream to diagnose a bad O2 sensor. The oxygen sensor is an important part of a car engine. An exhaust leak perhaps?. ACTIVE DTC. You can tell if Bank 1 is responsive by stabbing t. I'm getting an intermittent P013C code for passenger side downstream O2 sensor slow to respond rich-lean. About a week ago, I disconnected the battery overnight and the next morning I changed the upstream sensors. The O2 sensors are always located in the exhaust and monitor how much unburned oxygen is present in the exhaust. Sensor 2 is Downstream, after the converter. 3V but should be above 0. My wifes Sienna had a small exhaust leak at the front pipe and I feared it would be big bucks. Rear Oxygen Sensor. In most of those cases, the catalytic converter is perfectly fine - it is usually an exhaust leak, bad downstream O2 sensor (lazy sensor), or something else that is causing the CEL to come on. An oxygen sensor can malfunction anywhere from 30,000 to 100,000 miles depending on type and vehicle. Check the removed O2 sensor for damage from a defective catalyst and replace the catalyst if it is faulty. As I understand it, this sensor does not affect fuel trim but only monitors exhaust. 1v reading from the downstream sensor. 1 is usually the one in the exhaust manifold, while sensor No. If the PCM commands a rich mixture for acceleration, there is very little oxygen in the exhaust and the sensor PID will be less than 3. Downstream Sensor (Non-California Emissions): The downstream oxygen sensor (1/2) is also used to determine the correct air-fuel ratio. Replied by barneyb on topic Exhaust Leak Idle Issue The oxygen sensor compares the amount of oxygen in the exhaust to the amount in the ambient air outside the exhaust. Federal Emissions Package (4. Who is correct?. But there may also be benefits to replacing the O2 sensor periodically for preventive maintenance. Upon further research I concluded that the most probably issue was a bad O2 sensor. This is called the catalyst's "light off" temperature. Then, locate the catalytic converter at the center of your exhaust system and remove the oxygen sensor with a ratchet wrench. The OBD II system can't evaluate the converter if the upstream and downstream O2 sensors are not functioning normally. If any of these conditions are present you most likely will have a cold non-functioning converter emitting too much NOX or O2. If one or both of your upstream sensors are bad, and they failed in such a way that it isn't obvious to the computer, all it will know is that its readings from the downstream sensors don't line up with its expectation, hence the cat codes, rather than upstream O2 codes. Rear Oxygen Sensor. Remember that oil leaking onto older oxygen sensors will ruin the sensor’s calibration by sealing the shield vents against atmospheric oxygen. The waveform of the sensor behind the converter should be more steady). Condensation buildup can destroy a sensor very quickly, so mounting the sensor between 9 o'clock and 3 o'clock protects it from water build-up at the bottom of the exhaust pipe. The sensor measures the oxygen content of the exhaust gases and compares it to the oxygen proportion in ambient air, and sends information on the gases to the engine computer. 5 in exhaust gasket, and 30 minutes tops of your time to replace it. Did you know that more than 60% of smog or emissions test failures are the result of a bad oxygen sensor? If your car has a bad or defective oxygen sensor, it would be difficult to pass the emissions test, whether the check engine light is illuminated or not. Toyota Camry Oxygen Sensor Replacement costs between $133 and $672 on average. The A/F heater circuit is 4 ohms, specs say around 2 ohms. This is the long and thin cover toward the driver's side of the engine. For this reason, bad gas mileage can be both a symptom and a problematic result of a faulty oxygen sensor. O2 sensor faulty O2 sensor connection broken O2 sensor wire damaged (Melted by exhaust, rubbed through by drive belt, abrasion damage) AFR value for ONE cylinder reads LEAN (AFR = 16. Bank 2 sensor is working because it is fluctuating. O2 Sensor Wiring– Over time, the oxygen sensor wiring can go bad. well, whats really throwing me off is the extra sensor connector near the two o2 sensor connectors above the transmission. Consequently, This can quickly burn an exhaust valve. Specifically it'll usually be the O2 sensor(s) on the downstream side of the catalytic converter. I cut the pipe downstream of the cat, gutted the cat and reinstalled the cat, but have a leak where the pipe was put back together with a poorly fitting sleeve. There may be a third sensor downstream, if that is the problem, a P2274 is set. No combination of exhaust leaks can duplicate downstream and upstream sinusoidal oxygen sensor readings. If the converter is working at high efficiency, the downstream O2 sensor signal will be almost flat and show very little switching activity compared to the upstream O2 sensor(s). This reflects a RICH CONDITION. The high or low voltage signal tells the PCM the fuel mixture is rich or lean. United States Environmental Protection Agency Office of Air Quality Planning and Standards Research Triangle Park, NC 27711 EPA-454/R-00-025C May 2000 AiR EPA Final Report Hot Mix Asphalt Plants Truck Loading and Silo Filling Manual Methods Testing Asphalt Plant C Los Angeles, California Volume 3 of 8 Cleft® -i_ i v53rsiz. well, whats really throwing me off is the extra sensor connector near the two o2 sensor connectors above the transmission. Smoke test revealed no exhaust leaks from the manifold or any where else. Having a bad oxygen sensor can also send the the "Check Engine" light to go on or in more recent car model, send an O2 sensor code to the car's computer. I had a bad O2 sensor code, so I replaced the sensor. The upstream oxygen sensor is located in the exhaust pipe between the exhaust manifold and the catalytic converter The downstream oxygen sensor is located at the catalytic converter outlet. See here for a step-by-step guide on how to diagnose and fix check engine light code P0135. The downstream oxygen sensor should find a reading near center (about. The downstream O2 sensor is considered to be protected from extreme environments by the catalyst. To replace a catalytic converter, start by jacking the car up so that you can work underneath it. Who is correct?. Are they oxygen sensor codes or are they lean codes. If you notice increased emissions or worse fuel economy than normal, turn to AutoZone for a replacement oxygen sensor and exhaust manifold. The downstream oxygen sensor needs to have the wiring removed from the clip holding it in place, and then pulled out to install in the J hook style bung way at the bottom of the downpipe. P0136 is a generic code for types of trouble with oxygen sensors on "Bank One" of an exhaust system (FYI, if you have true dual exhaust Bank One will be dr. An oxygen sensor may or may not need to be replaced when an OBD code signals sensor issues. The P2270 DTC refers to downstream sensor (after the catalytic converter), sensor #2 on bank #1. Along with this, 20+ minutes of steady highway cruising always brought on P2096 & P0137 codes, both related to the rear O2 sensor. What is claimed: 1. 5 in exhaust gasket, and 30 minutes tops of your time to replace it. Dealer wants over $300 to replace and says if the sensor is not replaced, damage will occur to catalytic converters. Not even 3 days later i have the check engine light on again, i ran the codes, and same thing. My wifes Sienna had a small exhaust leak at the front pipe and I feared it would be big bucks. OP, I assume you mean the code was P2A00 which is the passenger side primary O2 sensor (Bank 1 Sensor 1). Check wire harness or connector (oxygen sensor - EFI relay): I am stuck here also. O2 (Oxygen) Sensor Signal Stuck Lean Bank 1 Sensor 3 This is a downstream O2 sensor and is exclusively used to it is common for a mechanic to miss vacuum leaks or exhaust leaks that will. The computer evaluates and compares signals from the upstream and downstream sensors to assess whether the cat. Ideally, your engine’s air-to-fuel ratio should be 14. ?Check for exhaust leaks at the manifold, pipes, catalytic converter. The P0171 is one of the more common trouble codes. A method for detecting an exhaust leak in an engine control system having an exhaust gas oxygen sensor upstream of a catalyst and an exhaust gas oxygen sensor downstream of the catalyst and an electronic engine control system for operating an internal combustion engine, including the steps of:. There could also be a vacuum leak in the engine causing this code. That's the answer then. Replace the O2 Sensor on the Catalytic Converter 1st. But there may also be benefits to replacing the O2 sensor periodically for preventive maintenance. Hooked a scan tool up and the new sensor is showing a voltage of between. Along with an upgraded exhaust manifold, improved oxygen sensors also keep your emissions within a normal range. I keep getting readings from my check engine light saying O2 sensors are bad. 500 volts) and it should hold this reading as long as the engine idles; If the downstream oxygen sensor fluctuates in a similar manner to the upstream oxygen sensor, the catalytic converter is most likely faulty. An exhaust leak can make your O2 sensors getting a faulty reading and may cause the code to trigger. If code P2096 returns then the problem is NOT with the downstream oxygen sensor. 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. I replaced both cats, the light soon came on again and it said it was my downstream bank 1 sensor. The downstream oxygen sensor should find a reading near center (about. *Confusing part: Apparently if your jeep (mine is a 2000) is NOT made in Cali, it will have 2 sensors (one upstream and one downstream). The waveform of the sensor behind the converter should be more steady). I know it's an O2 Sensor, but i just don't know what bank it is. I cleaned my maf as well. The oxygen sensors are threaded into the exhaust pipe near the engine and on some models are threaded into the exhaust manifold. A General Motors vehicle is being checked using mode $06 for the proper operation of the oxygen sensor. The Downstream O2 Sensor is considered to be protected from extreme environments by the catalyst. In the same way that the officer is controlling the flow of traffic, the O2 sensor has the final say on what is going on within the engine management system. This occurs by monitoring the change in the downstream O2 sensor voltage over time, when the fuel is sut off during a decel condition after the enable conditions were met. If the leak is occurring in the manifold gasket or the manifold flange gasket area, excessive heat can build up. Absolutely it can, the bogging is probably from the computer misinterpreteing the information from the o2 sensor, fix the leak, maybe replace the sensor (downstream o2 sensors often break upon removal, also check the sensors resistance while you're under there to make sure it's within normal range) and you'll probably be good to go. O2 sensor codes are often the most troublesome and misdiagnosed check engine light problems. In most of those cases, the catalytic converter is perfectly fine - it is usually an exhaust leak, bad downstream O2 sensor (lazy sensor), or something else that is causing the CEL to come on. This is done by removing a large vacuum hose and checking to see if the downstream oxygen sensor reports the vacuum leak. A wideband sensor works by comparing the oxygen left in the exhaust after combustion to the sensor’s reference pump cell which is referencing the. For pre-catalytic converter oxygen sensors used for fuel control: Less oxygen than optimal in the exhaust results in a signal voltage over 450 mV. Ideally, your engine’s air-to-fuel ratio should be 14. Shakiness on the highway is not related. Okay so I got the new oxygen sensor and I tried installing it today but I ran into a problem. Oxygen sensors detect the amount of oxygen content in the exhaust stream. It is constantly making a comparison between the oxygen inside the exhaust manifold and air outside the engine. After years of service, an oxygen (O2) sensor tends to firmly stick to the exhaust pipe or. Changing out your O2 sensors on your 4Runner is a pretty straightforward process that isn't too difficult to handle. This reflects a RICH CONDITION. How O2 sensors react to exhaust leaks: '01 Audi A4 In this diagnosis and repair of a blown flexpipe on an '01 Audi A4 Quattro we observe how an exhaust leak upstream of an oxygen sensor can. any extraneous air will cause the computer to think there is a problem. The middle oxygen sensor bung is used for an extra oxygen sensor if you install an air/fuel ratio gauge later. Each element is incredibly. If the leak is bad enough you should be able to hear a hissing noise while the engine is running. O2 SENSOR DIAGNOSIS. The post-catalyst oxygen sensors have an insulating foil shield. Okay so I got the new oxygen sensor and I tried installing it today but I ran into a problem. Normally, these two O2 sensors will have different readings when the car is running. Is there a gasket between the bracket and o2 sensor? I dont know if I should replace the part of pipe or just replace the gasket, if there is any. My jeep wasn't made in Cali. Can an exhaust leak cause your car to give bad readings? such as O2 sensors are bad? I have been having issues with my 99 Jeep Grand Cherokee 4. An exhaust system manages both pressure and vacuum cycles while an engine runs. Replace the Catalytic Converter. If you have P0171, or P0174 codes, they are not oxygen sensor codes. I located the sensor but don't know how to get. 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). Downstream Sensor (Non-California Emissions): The downstream oxygen sensor (1/2) is also used to determine the correct air-fuel ratio. The Possible Causes Of Rich Codes Are:. If that leak is upstream of the sensor, it will see the extra oxygen and set a trouble code. Position: Downstream. 0 V6 4WD for months now. to be able to operate properly. Thankfully, replacing it is relatively easy and inexpensive. My 2005 Buick LaCrosse runs smooth. Jeep Grand Cherokee 1999-2004: How to Replace Oxygen Sensor. If you know how to change an oxygen sensor on your 2000 Dodge Stratus, you not only save money in car repairs but avoid a much more expensive repair. It may be worth nothing that this just started a few days ago, before I changed the O2 sensor. How does an O2 sensor work? An oxygen sensor is a chemical generator. What is claimed: 1. Consequently, This can quickly burn an exhaust valve. Induce a lean condition to see if the downstream oxygen sensor reports it. I have my old manifold/Cat from when it got a crack in it a few years ago. Anyway I was thinking since the O2 sensor is after the exhaust leak could the leak be sucking air in causing the O2 sensor to think the engine is running lean and than tell the ECU to make it run richer? 94 pathfinder by the way Thanks. Changing out your O2 sensors on your 4Runner is a pretty straightforward process that isn't too difficult to handle. I ran my code reader and got code 420. The more the downstream sensor switches in relation to the upstream sensor, the less efficient the converter is at storing and releasing oxygen. O2 sensor performance codes and O2 heater circuit codes are two types of oxygen sensor trouble codes. Could I have an exhaust leak at my midpipe?. Normally, these two O2 sensors will have different readings when the car is running. Any O2 sensor that is defective obviously needs to be replaced. The upstream O2 sensor in the exhaust manifold reflects the condition of the exhaust gases as they exit the engine. If you know how to change an oxygen sensor on your 2000 Dodge Stratus, you not only save money in car repairs but avoid a much more expensive repair. This device is part of a car's emissions control system: it's roughly the size of a spark plug, and tests the oxygen levels in a car's exhaust stream. any extraneous air will cause the computer to think there is a problem. The signal from the rear oxygen sensor is used to monitor the efficiency of the catalytic converter. long periods of idle time can render a non-heated or older o2 sensor too cold for it to function at all. A General Motors vehicle is being checked using mode $06 for the proper operation of the oxygen sensor. 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. Make sure there are no exhaust leaks between the engine and the O2 sensor. RockAuto ships auto parts and body parts from over 300 manufacturers to customers' doors worldwide, all at warehouse prices. upstream sensor did not work in a 1999 buick park avenue. I went to a local shop and had a new thread welded on. I found a exhaust leak around the downstream o2 sensor, where the O2 sitting in bracket. For the first two times, I simply changed the O2 sensor. On 1996 and newer vehicles with OBDII, a downstream oxygen sensor monitors the efficiency of the converter and triggers the Check Engine light if the converter is not doing its job. As the O2 sensor measures the oxygen content of the exhaust gas to provide an accurate O2 reading, even a small pin-hole leak in a poorly welded sensor bung will effect the accuracy and performance of your O2 sensor. If downstream still shows lean then you are lean as both show the same trend. If the converter is doing its job and is reducing the pollutants in the exhaust, the downstream oxygen sensor should show little activity. Does post cat oxygen sensor affect gas mileage? This is a discussion on Does post cat oxygen sensor affect gas mileage? within the General Help forums, part of the LSx Technical Help Section category; My car has 210,000 miles now and I just realized that I still have the original O2 sensors. Engine light refuses o go out 36 Answers. Theory of Operation. It will produce a relatively stable. I have my old manifold/Cat from when it got a crack in it a few years ago. 800V My reading for Bank 1 sensor 1 (Wide Range O2) Equivalence Ratio is 1 and not changing. 2 is usually the downstream O2 sensor behind the 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). But there may also be benefits to replacing the O2 sensor periodically for preventive maintenance. This reflects a RICH CONDITION. I realized the white wires are the heater element, this checked out OK at around 6Ohms. Replacing an aging O2 sensor that has become sluggish can restore peak fuel efficiency, minimize exhaust emissions and prolong the life of the converter. As you know, a catalytic converter is a major part of the vehicle's emission control system. 48v while the other o2 sensor is between 0 and. Who is correct?. Ensure the exhaust gases file out of your vehicle properly with a premium exhaust manifold. The second sensor is usually further away from the engine down the exhaust system, but still close to the engine. This code is triggered by the first downstream (front) O2 sensor. The O2 sensor is mounted in the exhaust stream, usually with one sensor not far from the exhaust manifold and one farther down after the catalytic converter. I have my old manifold/Cat from when it got a crack in it a few years ago. An exhaust system manages both pressure and vacuum cycles while an engine runs. Oxygen sensors in general are normally located before and/or after the catalytic converter. To replace a catalytic converter, start by jacking the car up so that you can work underneath it. Depending on the emission package, the vehicle may use a total of either 2 or 4 sensors. Best case is that the smokey exhaust has coated the honeycomb inside, and the exhaust merely flows through, unobstructed.