The dark green/orange wire should have 12 volts. P0138 code definition. Oxygen Sensor. Why does my OBD-II scanner show the O2-#2 sensor reading in milliamps, not volts? I use am OBD-II scanner to read my O2 sensors. My intention was to compare the O2-1 (pre cat. Get a volt meter and check the voltage right at the O2 sensor. If you are getting on one reading, that means that the O2 sensor is not functioning properly. The oxygen sensor upstream of the catalytic converter will normally be referred to as Bank 2 O2 Sensor 1 (B2O2S1) and the downstream oxygen sensor will be Bank 2 O2 Sensor 2 (B2O2S2). Does anybody know the location to access the upstream o2 sensor? Thanks, Anthony. Depress and hold brake pedal to run the automated test. My gas mileage is horrible after the headers were put on. Like my post says, let me know if anyone has normal o2 sensor voltage values for a 2006. The rear sensor can be made to alter it’s voltage by simply snapping the throttle open and therefore commanding a rich mixture. Post cat O2 behind the cat should read be fairly constant, if the catalytic converter working properly. Eastern Catalytic manufactures catalytic converters, manifold converters and converter components for aftermarket and OEMs. Have a P0138 code on 2006 Rav4 (secondary O2 sensor). 95 volts instead of an expected 0. i have a check engine light on in my truck. Q - I do not have a bung in my new pipes, will this work for me? A - No, you must have a working sensor in the system. With the MAP sensor connected and the ignition in the “on” or run position, check the voltage output on the MAP sensor signal wire. The PCM (Powertrain Control Module) then compares the post-cat reading to the pre-cat readings to determine if the catalyst is working properly. A more complete list of oxygen sensor symptoms and their causes can be found here. Also be sure to check all computer grounds. First, remove the vacuum line or remove the MAP sensor from the intake manifold. Check engine back on in a few trips, same code. Q - Will this fix a bad sensor? A - No, you must have a working sensor. to control the same voltage for the Pre O2 sensors. wlb50 · Registered. My bank 1 O2 sensor reads constantly at 0. 0 while the pre-cat sensor sees fluctuations around 1. Physically, there's no difference between front and back O2 sensors. A properly working post-cat sensor will exhibit small changes at a slower rate than front o2 sensors. Order MINI Cooper Oxygen Sensor online today. 5V? The following image clarifies my question. P0138 is the OBD-II generic code indicating the O2 sensor for bank 1 sensor 2 fails to have a lower voltage output below 1. If it's not an intake leak, buy a $50 scanner and look at the voltages out of the MAF and both O2 sensors (although the post-cat oxygen sensor should not cause a lean code). Linear oxygen sensor control value. P2273 Bmw Description The Heated Oxygen Sensor 2 (HO2S) (Rear O2 Sensor), after three way catalyst (manifold), monitors the oxygen level in the exhaust gas on each bank. The voltage should be around 12-13volts and alternate, not stay the same. 7 volts Plugs all look to be running slightly lean. I was right and was able to get a better description of the fault with a far more advanced scanner than my hand held. An oxygen sensor, also known as an O2 sensor is a common part to fail and cause a check engine light on your car or truck. The universal oxygen sensor does not come with a connector which makes splicing necessary for installation. We reinstalled the Cat, and redid the measurements from the O2 sensor to the DME, and got a value of just under. What does Oxygen Sensor Post-Cat and Pre-Cat mean? oxygen sensor circuit voltage high. 1 catted headers they whipped up for me to connect to my SOUL cat-back already in use. Besides the main O2 sensor (called sensor 1) the ECU also incorporates a second and in some cases a third O2 sensor after the catalytic converter. Aygo O2 sensor codes OBDII and Torque app Since this post i have replaced the post Cat sensor, which improved the driving of the car quite a bit, the time for the. Because of the internal circuitry used in a wideband oxygen sensor, you can't hook up a voltmeter or oscilloscope to read the sensor's output directly. usually with a faulty o2 sensor, the engine will run rich not lean, as its the o2 sensor telling the ecu when ever it is lean. Obviously, replacing the sensor was not the proper fix. So what is Sensor 1? Sensor 1 is the O2 sensor that is located before or upstream of the catalytic converter. Scanned code P0138, bank1 sensor 2 voltage is too high. Pre Catalyst O2S Shorted to Voltage. The one that was in there was factory original. 0 Volkswagen engine. Replied by T. Linear oxygen sensor control value. A failed O2 sensor can set several different types of fault codes so it's a good place to start if you have O2 sensor or heater circuit faults. P0138 is the OBD-II generic code indicating the O2 sensor for bank 1 sensor 2 fails to have a lower voltage output below 1. Most late model vehicles will be equipped with both a pre-CAT oxygen sensor and a post-CAT oxygen sensor. Slow signal of precat exhaust oxygen sensor may prevent the post oxygen sensor emulator from working. My bank 1 O2 sensor reads constantly at 0. What rpm was the engine at? Bank 1 appears that it is doing something and the cat on that side is working. In other words, the new sensor acts more like a wide-band O2 sensor (read expensive) compared to the garden variety narrow-band O2 sensor. To measure voltage signals, use an analog voltmeter with a high input impedance, at least 10 megohms. The rear O2 sensor voltage fluctuates from around a peak of nearly 1 volt at WOT, to nearly 0 on decel. All four are active in air / fuel ratio feedback. 2 volts when the fuel mixture is lean (more oxygen in the exhaust). Where there's a Sensor 3, it's signal might be helpful in some cases. Well, that is interesting. After a couple hundred miles the check engine light came on with code P0037 which is HO2S heater control circuit low bank 1 sensor 2. Fuel trims are 4. Range is 0-0. Another point that can trip up an unwary technician is that the A/F value displayed on a scan tool can be misleading. Find Oxygen Sensors with Rear post-cat Oxygen Sensor Location and 0-1 V Voltage Range and get Free Shipping on Orders Over $99 at Summit Racing!. The oxygen sensor on a cars exhaust is used to determine how efficiently the fuel mixture is to an engine. 5 volt and fluctuate around that voltage at maintained engine speed of 2000 RPM when operating at normal operating temperature. The OEM sensor comes along with a connector which makes it like a plug and play device. Although it seems likely to me that the current RAM assisted AF-XIED will work for the O2 sensors ahead of the catalytic converter (meaning lambda-shifting will function), some testing is needed to determine whether the AF-XIED will do its job or be thwarted by the post-cat O2, and any limitations that the post cat sensor creates. If the O2 sensor is a traditional zirconia type sensor, the voltage output drops to about 0. 7:1 air/fuel ratio, the voltage reading of an air/fuel sensor will be around 1. The code was a P0138 Oxygen sensor input voltage maintained above the normal operating range. I currently have the bank 2 rear O2 sensor tied up and have the wideband in its place. I have a 2006 Taco with the 2. The car 'should' have an O2 before the cat. To the contrary, the air-fuel sensor will be at a stable voltage. 900V, adjusting from rich to lean detection. This may vary by model and the computer won’t registered a bad sensor until it fails a few times. Standard or "Narrow" Band Narrow band O2 sensors are typically found on earlier OBDII compatible vehicles as well as post-cat on newer models. O2 Simulators are only installed on the post cat (rear) oxygen sensors usually located at or slightly past the catalytic converter. To see 5+V on the output of an O2 sensor suggests a failed O2 sensor or bad wiring/connector between the O2 sensor and the ECU. Oxygen Sensor Output Voltage Bank 1-Sensor 1(V)0. Reason I ask, the post sensor is about $100 higher than the pre, they are both 4 wire, heated and look the same. Holden Cruze p2096 bank 1 sensor 2 lean fault description is post catalyst fuel trim system low limit. sensor for fuel trim but to monitor cat. hi all, this is in regards to a 2014 silverado with the 5. These are the original cats. My vag computer died so I am tring to diagnose with my. If the remaining oxygen content of the exhaust emission is 3 % (lean mixture), there is a voltage of 0. In many cars, the computer sends out a bias voltage of 0. If its B2 S2 that means Bank 2 (opposite Bank to Bank 1) and the downstream after cat o2 sensor. Physically, there's no difference between front and back O2 sensors. However, by taking the oxygen sensor off, you are able to visually inspect the sensor, which can often provide a good indication that there is a problem, and testing the sensor is also a little easier. If the sensor and connector are OK, replacing the O2 Sensor 1 usually takes care of the problem. What is the difference between a PRE Cat and POST Cat sensor? A. Hi all Ive had an intermittent CEL which has been diagnosed by my local Indy as as both rear o2 sensors. For 2nd generation MINI Cooper & S models including R56 Hardtop R55 Clubman R57 Convertible R58 Coupe R59 Roadster R60 Countryman R61 Paceman. The voltage reading from the post-cat sensors is compared the the voltage reading from the pre-cat sensors; the difference tells the ECU if the cats are working properly. Did replacing the post cat O2 sensor fix your problem? It looks like 3prongpaul provided good info on how to get to the plug if changing the sensor is the right answer to P0138. Hi, I would also like to disable o2 sensors after cat delete and putting headers on 330i, do I need to only off the following dtc : O2 sensor heater pre cat, O2 sensor heater post cat; o2 sensors voltage upstream and downstream ?. Wondering if it's. Order MINI Cooper Oxygen Sensor online today. My gas mileage is horrible after the headers were put on. 02:1 and the lambda is 0. I used one from Autozone (think it was a Denso) for 40k miles, until the secondary catalytic converter plugged up. However, the O2 sensors are not. A P0144 refers to a fault at the post-cat o2 sensor, indicating that the signal voltage is too high. The heater would engage after the voltage dropped below 1vish, and would trigger the readiness monitor. If anyone has been following my threads on getting this S600 escaped from a refugee camp in Sudan, you might remember I've not been able to get a correct mixture on one bank of the engine, as evidenced by the Lamda reading, and a direct voltage reading off the O2 sensor. 5 volts or higher. Usually rear o2 sensor problems won't cause drivability issues since they are an input that measures catalyst efficiency (unlike front o2 sensors). The purpose of the additional O2 sensors is to determine the efficiency of another key component of the emissions system: the catalytic converter (CAT). 4 v8 and runs well except for a lumpy idle. 9 volts (rich). The fuel economy of the car drops drastically. Using a gas analyzer, I quickly find that the air/fuel ratio is actually 14. So even if you have found that the oxygen sensor heater is faulty you should still check that the ECU is earthing the circuit after it is replaced. Am I able to use Diagbox or PP to measure pre. If Lambda fluctuates post-cat similarly to the pre-cat Lambda, the cat does not do it's job and a CEL results. 3 volts at 3750 rpm in 5th which is also fairly steady if throttle and speed are steady. To the contrary, the air-fuel sensor will be at a stable voltage. The connector not only is the supply for the voltage and grounds, but the source of the needed air supply to the zirconium sensor. Usually post-cat sensors aren't used for engine tuning, only as a 'confirmation' the cat is working. Then check the sensor voltage open loop and see what you get. 1 is pre cat and sensor 2 is post cat. My 850GLT is running too rich, which I believed initially was due too a defective primary o2 sensor. one of the first offered SOUL 987. A vehicle may have two to five oxygen sensors, and sometimes even more. P0031-O2 SENSOR 1/1 HEATER CIRCUIT LOW. 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. A fully warm O2 sensor *will not spend any time at 0. When the voltage is outside of the range, the code sets. 5V) for reference voltage to the sensor through one wire, and sensor ground to the other wire. What my issue boiled down to is the ECU was getting a reading of incredibly lean mixture from the O2 sensor. The O2 levels are monitored to see the efficiency of the burn process. Bosch recommends replacement of O2 sensors every 100,000 mi. Toggle navigation Back. In some instances, Sensor 2 can be pre-catalytic and thus making Sensor 3 post-catalytic. They are there only to monitor the performance of the catalytic converters. It will read an accurate mixture, usually, but not necessarily, a voltage of 0. The post-cat sensor is always a standard oxygen sensor. The post-cat O2 sensors are identical to the pre-cat O2 sensors (same voltage outputs). I do not know if Subaru's kick a O2 specific code or it throws O2s, cat other emissions problems into the P0420 code? with that said the front O2 sensor is the main sensor the engine uses, the rear more or less serves as a secondary check. Post cat O2 sensors feed back 0. Replied by T. 00V at idle. Some vehicles have pre and post catalytic converter sensors (upstream and downstream). Code P0138: O2 Sensor Circuit High Voltage (Bank 1, Sensor 2). I am hesitant to replace Post-cat O2 sensors as PM because often lazy Post-cat O2 sensors mask or hide P0420/P0430 catalytic converter efficiency errors. After a couple hundred miles the check engine light came on with code P0037 which is HO2S heater control circuit low bank 1 sensor 2. i have a check engine light on in my truck. I pulled that O2 sensor, and scanned a P0138 high voltage for that sensor (keep in mind I am not driving the car around). P0138 is the OBD-II generic code indicating the O2 sensor for bank 1 sensor 2 fails to have a lower voltage output below 1. So all a post-cat O2 sensor has to do is to monitor that Lambda stays steady at 1. Bank 1, Oxygen sensor voltage [%] [V] 033. 9 volt at idle. Jump to Latest Follow 1 - 15 of 15 Posts. My rear O2 ses light is turned off in the tune. Fuel trims are 4. 7:1 air/fuel ratio, the voltage reading of an air/fuel sensor will be around 1. If the output wire of the O2 sensor is open, the input on the ECU may float high, thus the high reading. If anyone has been following my threads on getting this S600 escaped from a refugee camp in Sudan, you might remember I've not been able to get a correct mixture on one bank of the engine, as evidenced by the Lamda reading, and a direct voltage reading off the O2 sensor. And that person “accicdently” took out their cat’s and replaced them with a straight pipe wich. It's one of the most important discoveries for the car, and happened in the mid to late '70s. Since this code means high signal voltage from post cat. 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. The o2 sensor is a four wire sensor. Aygo O2 sensor codes OBDII and Torque app Since this post i have replaced the post Cat sensor, which improved the driving of the car quite a bit, the time for the. Below are the recorded graphs while I was driving with new O2 sensor. The adjustment knob is at the left, and the switch is on the right. I wouldnt go throwing money at a new sensor until you know for sure that its at fault. There are other possibilities besides bad sensors that will set these kinds of trouble codes. 74v mainly). Air-fuel sensors are only used for fuel control, so they are always a pre-catalytic converter sensor, not a post-catalytic converter sensor. 2 fault codes are logged, O2 sensor circuit, Bank 1 sensor 1 (P0130) and O2 sensor heater circuit, Bank 1 Sensor 2 (P0141) According to the data stream, O2 sensor 1 sits at around 0. I am not sure if it will come back, but based on previous experience with this code it likely will. The CEL will come on if the secondary O2 sensor itself fails. And that person "accicdently. 1 V due to the difference compared with the oxygen content of the ambient air. Add some extra fuel to the intake, propane works good, or simply a squirt of gas down a vacuum hose will do. I look at the B1S2 sensor and the voltage reading is BARELY moving. after the mini-cat towards the rad / forward -bank one is the front, it's right behind and above the front diffI just changer both my lower O2 sensor's and it took about 20 minutes total, you'll want an O2 sensor socket an extension / wobble - I took a wire brush to them before I changed them out. Buy Hilitand 4 Wire O2 Oxygen Sensor for Vauxhall Corsa C D 1. A ratio that has too much oxygen in it is said to be lean, whereas a ratio with too much fuel is said to be rich. When the fuel mixture is rich (less oxygen in the exhaust), the sensor's output jumps up to a high of about 0. Hi all Ive had an intermittent CEL which has been diagnosed by my local Indy as as both rear o2 sensors. If you'd read carefully enough you'd know that I never said anything about the wire being broken affecting the oxygen flow to the internal portion of the O2 sensor. hi guys its been a while im looking for a learned member who knows his shit about electronics and how to make these 02 sims or cel eliminators i know the rear 02 sensor ranges from 0. The solder biases the voltage reading and this can. P2273 Bmw Description The Heated Oxygen Sensor 2 (HO2S) (Rear O2 Sensor), after three way catalyst (manifold), monitors the oxygen level in the exhaust gas on each bank. Unleaded fuel is essential to the proper and continued operation of the O2 sensor. There area four sensors two each bank , front two are air fuel ratio and rear two ( after cat) are o2. Make sure there are no engine problems first, otherwise the new converter will be damaged. In the US starting around the mid 70's, passenger vehicles that have an internal. What is the life expectancy of an oxygen sensor? Heated oxygen sensors should be checked or replaced every 60,000 miles, while unheated or one wire oxygen sensors should be checked or replaced every 30,000 miles. This sensor is used to fine-tune the air-fuel ratio to maximize catalyst efficiency. 0T that the bank 2 post cat sensor has aged and is retarded, I proceed to indent the post cat sensor part number 06E906265AA. with throttle steady 2000 rpm and engine fully warm the voltage should be in the range of 60-85mv steady reading with very few fluctuations. Its voltage depends on the amount of oxygen in the exhaust stream. Because the oxygen sensor generates its own voltage, never apply voltage and never measure resistance of the sensor circuit. 2 volts for more than 10 seconds indicating a lack of oxygen in the exhaust stream. One of those sensors is probably not doing its job. Signal, Oxygen sensor post Cat. The post-cat sensor is always a standard oxygen sensor. An oxygen sensor, also known as an O2 sensor is a common part to fail and cause a check engine light on your car or truck. Dallas1215 on topic O2 Sensor Running Rich? 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. First O2 Sensor Basics video:. I got CEL, VSC, 4WD lights on. The best part is, our Toyota 4Runner Oxygen Sensor products start from as little as $31. P0138 code definition. P2138 – The values from the position sensors of the accelerator pedal are implausible in relation to each other. Oxygen sensor simulator is a racing part. com P0430 hack. If the catalytic converter is bad, the post-cat oxygen sensor will mirror the post-cat oxygen sensor. I checked for exhaust leaks (I used to have one behind the cat, but sealed it) & replaced the rear O2 sensor with an OEM Denso bought from Amazon a few w. I have 99 Suburban replaced all O2 sensors couple years ago. BMW documentation says they use post cat sensors on some engines to make fuel trim adjustments but nobody replaces post cat sensors unless they have cat efficiency codes. Reason I ask, the post sensor is about $100 higher than the pre, they are both 4 wire, heated and look the same. Tells the computer if the car is running rich or lean, so the computer can control the fuel injection (or CCC carburetor) to a stochiometric ratio (14. In general, after year 2000 most car manufacturers uses the post-cat O2 sensor to provide additional emission feedback to the ECU. Get a volt meter and check the voltage right at the O2 sensor. Well, that is interesting. I understand o2 sensors give out different voltage, but I want to make sure this isn't a way to get someone to pay an extra 100 for the same sensor, just by. The O2 sensor is active anytime it is hot enough, but the computer only uses this information in the closed loop mode. MINI factory replacement O2 Lambda Sensor for pre and post cat (sold individually). Post-cat sensor 1 voltage monitoring: Oxygen sensor after cat. Because the oxygen sensor generates its own voltage, never apply voltage and never measure resistance of the sensor circuit. Symptoms of a bad O2 sensor? below that Sensor 2 has a constant voltage and does not change where as sensor 1 jumps all over the place. 000 km/h 2CA3 DME: Oxsygen sensor heating before catalytic converter excessively low overrun signal voltage Fault currently not present. I've fixed the harness, but the sensor still shows as bad. It is my hope that this short oxygen sensor article will open your mind on the subject. When I first bought the car I scanned it and found the codes might have been cleared previously, and I was getting a P0137 O2 circuit low voltage on Bank 1 Sensor 2 (driver side post cat). Where there's a Sensor 3, it's signal might be helpful in some cases. Hi all Ive had an intermittent CEL which has been diagnosed by my local Indy as as both rear o2 sensors. The computer then uses this information to recalculate the fuel delivery depending on what is needed. Checking a MAP Sensor. O2 sensors (pre and post cat) difference? Is there a real difference between o2 sensors pre and post cat or is it just reffering to the location? What I'm asking is, since both my o2 sensors need to be replaced. The median is. O2 Sensor Signal Simulator for ford Mustang 1996-2004 GT Cobra 4. Can anyone confirm the oxygen sensor configuration on a 1. 0 volt or a pulse-width modulation (PWM) signal that is proportional to the air mass flow rate, and both sensors have an intake air temperature (IAT) sensor incorporated into their housings for most post on-board diagnostics (OBDII) vehicles. 6 V8 SVT Bypass Kit Exhaust Kit CEL. I was reading a thread in the BenzWorld site. It is my hope that this short oxygen sensor article will open your mind on the subject. i have a check engine light on in my truck. Turns out the actual fault/issue's source is with the after cat o2 sensor. Disconnect the connector and remove your post-cat O2 sensor. The lambda sensor is fitted into the exhaust pipe before the catalytic converter; cars using the new EOBD2 will also have a post cat lambda. uk Forum » Road Cars » Clio » Would a Faulty downstream post cat lambda sensor-. 1 volts during the first 2 minutes of operation. causing enough of a voltage drop in the ground side of the sensor circuit to keep the engine computer on guard. Checking a MAP Sensor. Over time an oxygen sensor make become "lazy". For 2nd generation MINI Cooper & S models including R56 Hardtop R55 Clubman R57 Convertible R58 Coupe R59 Roadster R60 Countryman R61 Paceman. Primary fuelling on a wideband car is done by the pre cat wideband sensor. 45 volt (450 mv). if you have a scanner with some live data, get that going and look at the voltage of the b1s2 o2 sensor, if it hovers around 0. Hi all, Hoping someone can help. 45V if the catalytic converter is functioning properly. My check engine light comes on after about 5 minutes of driving. One of the things a lot of mechanics neglect to check is probably the easiest thing to check — the O2 sensor connections. 5 volts or higher. How to replace pre-cat BMW E46 M3 (O2) sensor DIY Check engine came on found faulty O2 Lambda sensor on my E46 M3 so thought I'd post a few pics to help others. P0138 B1S2 Oxygen sensor circuit high voltage. when i rev the engine up, the first sensor shows a voltage change, but the other one still stays at 4. I have verified that if I pull the pins out of C19/C20 in the PCM connector and plug them into my DVM, I can use my propane torch and make the o2 sensor go back and forth between 0. What the Home Mechanic Needs to Know about O2 Sensors Download PDF. The OEM sensor comes along with a connector which makes it like a plug and play device. I do not know if Subaru's kick a O2 specific code or it throws O2s, cat other emissions problems into the P0420 code? with that said the front O2 sensor is the main sensor the engine uses, the rear more or less serves as a secondary check. TAT POLL: VIEW LATEST POLL. 8 volts at a rate of roughly one complete cycle every 2 seconds. I've fixed the harness, but the sensor still shows as bad. O2 Simulators are only installed on the post cat (rear) oxygen sensors usually located at or slightly past the catalytic converter. R129 - learning a bit about O2 sensors & codes. Our Universal, Direct-fit, CARB, High Performance and Diesel converter lines cover over 100,000 applications, including OBDII coverage for all 50 states and are certified in 58 countries around the world. I Have Intermittent Check Engine Light P0420. With the MAP sensor connected and the ignition in the “on” or run position, check the voltage output on the MAP sensor signal wire. A P0156 code definition:the Bank 2,2 o2 sensor or the downstream (post-cat) o2 sensor on Bank 2. They are there only to monitor the performance of the catalytic converters. Essentially the same as P0137, a P0136 code refers to the second oxygen sensor on Bank 1. For optimum catalyst operation, the air-fuel mixture (air-fuel ratio) must be maintained near the ideal stoichiometric ratio. 67 mustang coil wiring diagram together with s stang mustang forums attachments ignswwiring 220602 together withstrategiccontentmarketing co wp content uploads 2018 08 ignition coil wiring diagram enticing reference ford motor inside exceptional distributor 1 on chevy 350 ignition coil wiring diagram furtheraveragejoerestoration resources mustang wiring and vacuum diagrams 1967 mustang wiring. The theory is that the converter should be capable of storing extra oxygen that comes in when the mixture is lean (low upstream HO²S voltage) and releasing it when the mixture is rich (high upstream HO²S voltage). wlb50 · Registered. the post cat sensor is there as a cat check basicaly from what I understand, by checking pre and post cat emissions it can detect when the CAT is no longer working / failling. 015v but then went straight back up again. The 2nd DIY circuit would be for the Post O2 sensors, adjusting the same signal to both post O2 sensors, using the true feature of a. It serves no fuel control purpose. Because the oxygen sensor generates its own voltage, never apply voltage and never measure resistance of the sensor circuit. This isn't in reference to the Oil and Gas industry, this is an automotive question. What does the secondary O2 sensor really do?. 47 volts, even while driving. Most likely the part will have to be ordered. For the 1st generation MINI Cooper and Cooper S models including 2002-2006 R50 & R53 Hardtop and 2005-2008 R52 Convertible. O2 Sensor – image courtesy of wikipedia. converter of a broad band sensor. The rear O2 showing zero voltage. On V6 and V8 applications with dual cat exhausts, you'll have upstream O2 sensor readings for each side of the engine and downstream O2 sensor readings for each converter. The O2 sensor sends an electric signal directly in proportion to the oxygen content in your vehicle's exhaust stream. sensor for fuel trim but to monitor cat. P0420 Catalyst System,Bank1 Efficiency Below Threshold Ok so I've searched all over and seems like everyone that gets this code had an aftermarket exhaust. Increase the engine RPM to a fast idle and then recheck the sensor voltage reading. What kind of simulator do I need or can I just remove the whole sensor. So that is good. What my issue boiled down to is the ECU was getting a reading of incredibly lean mixture from the O2 sensor. With the key on, check for battery voltage to the O2 sensor connectors. Wondering if it's. Can you provide correct parts number of the O2 sensor for my E90 335i ,thanks. This can look like the o2 sensor is following the pre-cat o2 sensor by having a similar profile as untreated exhaust, but really it's just a bad sensor. I have intermittent check engine light p0420. It is now clear why the post cat oxygen sensor voltage is high, the vehicle is truly running too rich. 2 volts when the fuel mixture is lean (more oxygen in the exhaust). I purchased this sensor to replace one of the two post-cat o2 sensors in my 2001 BMW 325i (the second sensor I purchased was "Bosch 15681 Oxygen Sensor, OE Type Fitment"). So BN cats too. If there is no reading or if the sensor voltage is not changing, then it indicates a bad or sluggish O2 sensor that needs replacing. 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. The voltage is transmitted to the engine's computer. The engine RPMs should raise to around 1400. What kind of simulator do I need or can I just remove the whole sensor. For 2nd generation MINI Cooper & S models including R56 Hardtop R55 Clubman R57 Convertible R58 Coupe R59 Roadster R60 Countryman R61 Paceman. Free Same Day Store Pickup. The explanation is complicated but the short version is the ECM is using the post catalyst reading to verify proper fuel control as indicated by the pre-cat sensor. Further to my video about upstream sensors, here are a few points relating to downstream (after cat) O2 sensors and using them for some basic tests. 7v slightly wavering being the sweet spot to make the ecu think the cats working normally ive read conflicting over seas info online to use a capacitor a diode. Post cat is aftercat, these are for catalytic working yes or no ONLY. It's one of the most important discoveries for the car, and happened in the mid to late '70s. Joined Mar 9, 2013 ·. New behind the cat (Bank 1, Sensor 2) O2 sensor did not fix it. Sensor 2 seems to sit at a constant 0. The sensor voltage fluctuation and high fuel trim values reported by the post-cat O2 sensor were unchanged. Thus pre and post "cat" (Catalytic Converter) What does O2 sensor mean on Isuzu Rodeo? Bank 1 (same side as cylinder #1) sensor 1 (before catalytic converter) oxygen sensor circuit voltage high. On the other hand the oxygen sensor which is placed after the catalytic converter/s is used by the ECM primarily to determine catalytic converter efficiency. If the downstream O2 sensor activity mirrors the upstream O2 sensor, the converter is dead and needs to be replaced. Often one will be a Wideband sensor, and the post-cat sensor will be a 4 wire Zirconia type. Prior to 2000, the post-cat 02 sensor was mainly used to gauge cat efficiency. How to Change an Oxygen Sensor. but if the voltage jumps up and down the cat is doing nothing and needs to be replaced. So that is good. Bank 1, control value. Testing the O2 Sensor. If you have a voltage meter you can test for proper voltage at the front O2 sensor wire harness. Can I use Lexia to measure pre and post cat O2 sensor voltage? I have a copy of Lexia for my Citroen's and Peugeot's. However, if the O 2 sensor harness voltage shows battery voltage on both heater wires (with the light still connected), locate the possible open circuit in the sensor’s negative wire.