I'm certainly not an expert, but the short term trim values seem reasonable on both banks. Keep in mind that the downstream, post-catalyst oxygen sensor can often be used to differentiate between an ignition- or fuel-related misfire. If the post cat O2 sensor's voltage fluctuates too rapidly (like the pre-cat O2 sensors are supposed to), that triggers the P0420. Try richening your injector compensation and see if you can get the O2 sensor to move. Re: Check Engine Light Code P0421 on my 99 CA Emissions. Step One Install the Wideband O2 Sensor. If you can't do this easily, try just raising fuel pressure as a temporary test. I'm not sure I agree with your comments about leaving the O2 sensor in the pipe when O2 is not enabled. The graph below shows approximately 1 minute of data while cruising at a steady speed of 55mph. slower is better on rear sensors. STFT (short term fuel trim) is the instantaneous response of the ECU to reduce or add fuel to maintain an ideal combustion mixture. If available, the factory O2 sensor location is usually preferable. Hooked up an Innova 3130 to the ODB port. The problem didn't move with the sensor. In the above we have the following pids graphed. I somewhat knew it was used for cat efficiency, just not exactly how. The difference between the oxygen levels of the exhaust relative to the oxygen levels of outside air creates a voltage to flow inside the O2 sensor, and this reading is then relayed to the vehicle CPU. Changing it brought my mpg up to 18 in mixed flogging. The graph of narrow band O2 sensor voltage on this page shows swings that are far more consistent than what your graph shows. Under these conditions, expected sensor life will be less than 10 hours. The second O2 sensor voltage will then creep up slowly from 0V to 0. Is the correct upstream O2 sensor for a 2004 I6 Chevy trailblazer part number 21054 from rockauto? I bought an AC Delco from them and when the part came it was stamped NTK on the oxygen sensor. Consequently, the downstream zirconium sensor produces a constant voltage generally in the 600-700 mV range. - O2 sensor 2 (Is this downstream?) was quite stable around 0. As fuel quantity decreases we return to a lean mixture, and sensor voltage drops. From what I thought the o2 sensors for sensor 2/down stream was supposed to show fairly strait line for a good cat, though in this, it looks like they are everywhere. They have the same plug, but the cable lengths are different. This means the sensor is operating properly. Downstream Heated Oxygen Sensor Heater Failure. I've been unscrewing sensor since 30 years before I was even born and never once have I seen replacing a downstream O2 sensor make a cat code go away. P0161 is : Downstream Oxygen sensor bank 2 HEATER circuit malfuntion/low voltage It's not a lean code. It monitors the heater circuit, switching voltage and rise/fall time of the sensors. Downstream Right Oxygen O2 Sensor 234-4902 Bank 2 Sensor 2 Compatible with Chrysler Crossfire 3. On the K4M be careful - the downstream O2 is also contributing to fuel control and its not only looking after the CAT's condition You seem to have a working scanner - post a upstream O2 sensor voltage graph with the engine idling just after a cold start and also with the engine idling after a warm start. I logged the front O2 versus the rear O2 sensor, and they seem to corrolate just fine, but the graphs of the sensor data is like a giant wave over and over. If you were to graph the voltage, it would be pretty much a straight line. Here are 3 pics - vertical screen cap, horizontal, and one when I give it some gas/throttle. A "cold" engine makes the computer change the fuel air ratio so the output voltage of the o2 sensor switches between about 100 and 850/900 mV and after a while the sensor may output a switch voltage between about 200 and 700/750 mV, for turbocharged cars even less. Check the voltage of the sensor, everything checked out so I dried the downstream O2 sensor using a hair dryer and turned off the code; never came up again. Sensor 1 is a planar dual-cell limit current sensor and is designed to output a near constant voltage of 1. P0138 O2 Oxygen Sensor Circuit High (B1S2) Technical Description. I have a scan tool that can graph o2 output. Wideband sensors don't have that rapid switching, that chart looks like a narrow band sensor. This also means that the high voltage the downstream O2 sensor is reporting is being caused by a genuine Rich condition. The transition is quick and abrupt, so the PCM has to keep track of the back and forth rich/lean transitions to estimate the average air/fuel mixture. Sensor 2 is conventional O2 sensors, not wideband A/F sensors. That's when I started getting the P2096 code. Excess oxygen in the form of regular ambient air will send the O2 sensor voltage signal low (under 0. 3rd Gen Ram Tech - 2004 5. Upstream sensors actually control the air to fuel ratio, downstream sensors only purpose is to check catalyst performance (used to check effeciency of the catalytic convertor) if the converter fails or is removed both upstream and downstream will. oxygen sensor function, upstream and downstream by BillyGtr | April 30, 2009 1:47 AM PDT I have a 1997 Jeep GC Ltd 4WD 4. I may have a pin hole leak downstream of the rear sensor but I am asking if that outside air could reach the o2 sensor would there be voltage dithering or would it just peg to rich? Pretty sure it would peg high in the v range. 0 volt range. I know sensor 1 is the engine management sensor and sensor 2 is the emissions monitoring sensor. 9v that does indicate a failed CAT or major exhaust leak (unlikely). Bank #1 is the side of the engine that contains cylinder #1. For years, we've been using oxygen sensors as a tuning aid, hooked up to one of many aftermarket display gizmos that convert the sensor's voltage to a comprehensible reading. I got one from amazon 90 bucks. Better EGR and fresh charge air mixing resulting from introducing the mixture upstream of the turbocharger compressor. This review highlights the influence of oxygen (O 2) availability on cerebral blood flow (CBF). This is neither rich nor lean. Even though in the emissions check, the program is showing a green COMPLETE for O2 sensors and O2 sensor heaters, the real-time readings screen is showing 0 MV for both O2 sensors. 6 V, if the second O2 sensor and catalytic converter are good. The ECM uses the signal from the front and the rear oxygen sensors to control the engine operation and to monitor the performance of the catalytic converter, which is a major part of the vehicle's. I was almost tempted to swap sensor #1 and Sensor #2. Suzuki Grand Vitara Oxygen Sensor Your Suzuki Grand Vitara will be happy to know that the search for the right Oxygen Sensor products you’ve been looking for is over! Advance Auto Parts has 42 different Oxygen Sensor for your vehicle, ready for shipping or in-store pick up. Mount the wideband oxygen sensor before the catalytic converter and at least 24 inches downstream from your engine block or turbo. 04 volts most of the time except for full throttle and then it jumps to 750 where it belongs. All O2 sensors are vented to the atmosphere which contains Approximately 21% oxygen. My Nissan service manual states that the P0420 code is set if the frequency of the downstream sensor switches at a rate of 75% or more of the rate of the upstream sensor. Since oxygen sensors are not cheap and sometimes the PCM (Powertrain Control Module = Fuel Injection Computer) accuses them of being BAD, when they aren't, testing them is a good idea and this article will help you. Even though in the emissions check, the program is showing a green COMPLETE for O2 sensors and O2 sensor heaters, the real-time readings screen is showing 0 MV for both O2 sensors. also a good way to test is if you have a scan tool that can graph live data watch the rear o2s and see how quickly they are switching high to low voltage. A downstream oxygen sensor in or behind the catalytic converter works exactly the same as an upstream O2 sensor in the exhaust manifold. 2 Complete and Signal-only Installations. A worn-out oxygen sensor can cause engine performance problems and shorten the life of the catalytic converter. The 2004-2005 LeSabres appear to use different O2 sensors than the 2000-2003 LeSabres, making my graphs less useful than I'd hoped and possibly explaining why your upstream and downstream O2 sensors "drop off" in voltage after KOEO when the 2005 LeSabre's do not (i. The downstream sensor usually has no impact on fuel trim like the upstream ones. 932V (highest) at 2000rpms, the waveform was very regular, same height and depth spikes everytime, it was a bit less rapid a change at idle. Sensors like the MAF, O2 Sensor, Wheel Speed Sensor, Knock Sensor, Crank and CAM Sensor, and all the other most common sensors are covered. Workings of a broadband oxygen sensor. The next step in testing your crankshaft sensor is to check for continuity between your Civic’s chassis ground and the CKF sensor at both terminal 3 and terminal 1. Bad O2 Sensor Graph Readings » thanks for visiting our site, this is images about bad o2 sensor graph readings posted by Benson Fannie in Bad category on Oct 12, 2019. The broadband planar zirconium oxide air fuel sensor is a combination of a standard oxygen sensor and a pump cell that samples exhaust gas. 45 through the O2 sensor wire. If the back sensor switches back and forth like the front one, the converter is bad. Testing Oxygen Sensor In Jeep Liberty » This is images about testing oxygen sensor in jeep liberty posted by Maria Nieto in Testing category on Oct 12, 2019. Sensor 2 is conventional O2 sensors, not wideband A/F sensors. This dodge neon has code P0132 ( o2 sensor circuit high voltage B1S1 ). I am not sure what this reading is though, it says on my scanner software "O2 wideband bank 1 sensor 1 voltage" I really don't think that is 18,000 volts. Consequently, the downstream zirconium sensor produces a constant voltage generally in the 600-700 mV range. This is the voltage graph pattern of a brand new installed downstream O2sensor which shows the ideal pattern, a rich steady line with not much fluctuation. O2 Sensor revisited. To evaluate the health of the sensor and confirm the diagnosis, we observed the sensor voltage while accelerating and decelerating. First Generation Ridgeline (1G 2006-2014) 1G Problems & Issues. The problem with reading the live scan data as presented is that it is either a snap shot of 4 pids or a graph of 1. These sensors are current devices and do not have a cycling voltage waveform. This means the sensor is operating properly. The first generation platform has been proven in many others for the measurements of O2, CO, CH4, NH3, H2O and many more NIR absorbing gases. Toyota RAV4 Service Manual: Oxygen sensor circuit. I recently fixed two broken exhaust manifold studs on the passenger side, and I was hoping that would clear up my issue, but it doesn't seem to have helped. PO132 is Oxygen Sensor Voltage High bank 1. To learn about ECU/PCM, I've used the SC tuner to run datalogging and recently bought a Foxwell 301 diagnostic tool that graphs voltage. It is a four wire sensor. From Frank's last diagram, this is consistent with a properly working cat (and presumably working O2 sensors). 7L GM vehicle is not that hard to do. OBD2 Fault Codes - Poor Lamda sensors. Learn what does P0420 Honda Catalyst System Efficiency Below Threshold Bank 1 means, location and how to repair? The Engine Control Module (ECM) monitors the switching frequency ratio of heated oxygen sensors 1 (front O2 sensor) and heated oxygen sensors 2 (rear O2. 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. sensor calibrations. Sensor 1 is a planar dual-cell limit current sensor and is designed to output a near constant voltage of 1. Graph of the upstream (O2S11) and downstream (O2S12) oxygen sensors under acceleration and deceleration. Your car may also have wideband O2 sensors and they do not have the same read out as a standard O2 sensor. A vehicle with a bad cat. 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. If the downstream O2 sensor reading is fluctuating from high to low like the front sensor, it means the converter is not functioning. MINIDIS ADXpert performs according to ASTM D7344, the New Mini-method for the Distillation of Petroleum Products at Atmospheric Pressure and generates detailed D86 test reports. I cannot stress enough, do not simply cut the wires in your stock harness and crimp on some longer bits of wire. The data from this sensor is compared to that of the upstream sensor. O2 Sensor Questions I recently had LG Pro headers put on my C6 but didn't have the o2 sensors at the time. Therefore, given that the sensor is supplied with a 5 V reference, a rich mixture will cause a high voltage output, around 4. View and Download Matco Tools FixAdvisor MD70 operating instruction online. This sensor measures the pollutants making it through the converter and out of the tailpipe. Usually a narrow band is used as the upstream and downstream O2 sensor in most vehicles, but some cars do use a wideband upstream sensor like the post 2005 Impreza. If the O2 sensor only produces a low- or high-voltage signal, either you have an engine performance issue or the oxygen sensor stopped working. Excess oxygen in the form of regular ambient air will send the O2 sensor voltage signal low (under 0. Scroll to Bank 1 Sensor 2 and take a look at the voltage. Set 'Graph Item 1' to 'O2 voltage (Bank 1, Sensor 1)'* - this is the oxygen sensor BEFORE the catalytic converter and the upstream flow; Set 'Graph Item 2' to 'O2 voltage (Bank 1, Sensor 2)'* - this is the oxygen sensor AFTER the catalytic converter and the downstream flow; Repeat steps 2 & 3 if you have 3 or 4 oxygen sensors in your vehicle. The P0420 and P0430 codes are set by the ECM using the downstream or secondary O2 Sensor. 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. Lean to rich threshold voltage. Since this is a wideband A/F sensor, I do expect voltage above 1V. Morning all, After the EML came up, pulled the codes and had various errors for Bank1 O2 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. the ECU is getting no input whatsoever, i. Not sure what the trigger is for those codes, but the description implies the PCM is complaining about the O2 sensor readings for some reason. The rear O2 sensor is just a diagnostic O2 sensor for this trouble code. If that's what has happened, it will be very obvious if you watch a graph of the "O2 sensor voltage" on the "bank 1 sensor 2. 7:1 the voltage hovers around. I somewhat knew it was used for cat efficiency, just not exactly how. So maybe the #1 sensor is "lazy" causing the fuel mixture to be off resulting in the correct reading downstream. Excess oxygen in the form of regular ambient air will send the O2 sensor voltage signal low (under 0. slower is better on rear sensors. 5 V6 102k miles. The way this happened to me is I accidentally plugged in an O2 sensor eliminator into the sensor, the harness connectors are the same. I'm a bit surprised it's this one, since the Bank 1 Sensor 2 reading does not change much, and I would have thought it was the bad one. From what I thought the o2 sensors for sensor 2/down stream was supposed to show fairly strait line for a good cat, though in this, it looks like they are everywhere. Low O2 voltage is lean, high O2 voltage is rich. Multiple sensors are also increasingly common, with manufacturers installing a sensor on adjacent pairs of cylinders on four cylinder engines, and on each bank in V6 engines. a bit over. The catalytic converter works to maintain the stoichiometric air-fuel ratio 14. Also, why is there no value for "02 volts Bank 1 Sensor 1"? I ran a graph of live data and it shows pretty much the same. A downstream oxygen sensor in or behind the catalytic converter works exactly the same as an upstream O2 sensor in the exhaust manifold. 3 V6 CPI (with leaking poppet valve tube, SFT 89, LFT 108) 94 Ford 5. The resistance is low with low O2 concentrations (rich mixtures) and high with high O2 concentrations (lean mixtures). As the sensor degrades, free air calibration will become impossible. After that, it read O2 Sensor - Bank 2 Sensor 2 - Low Voltage. So the O2 voltage should drop briefly before the short term fuel trims rise to compensate. There is a slight possibility of a minor exhaust leak 12 inches after of the second O2 sensor. Sensor 1 is a planar dual-cell limit current sensor and is designed to output a near constant voltage of 1. That being said, according to the Nissan Shop Manual the correct voltage for the AIR/FUEL RATIO SENSOR should be 1. from what I've read, I believe the graph should look like front o2 sensor #1 in my graph, not front o2 sensor #2 which is way up and down. Low sensor voltage for switch time calculation. The data from this sensor is compared to that of the upstream sensor. If I am reading things right, this is saying really lean. ETA - since it's a Toyota, the front sensor may be a air/fuel sensor instead of an O2 sensor. Late Model Restoration carries a full line of Fox Body restoration and performance parts from top names in the industry. I could do a voltage drop test, but I don't think it will yield much. This will mean that the voltage readings from the monitoring O2 sensor will be flat and will not switch up and down like the primary sensors do. For these applications, the iO 2 SS can intercept and augment the downstream O 2 sensor's signal by adding a user-configurable amount of positive or negative voltage offset. Try richening your injector compensation and see if you can get the O2 sensor to move. A sensor with a dirty sensing wire or not measuring all the air (air leak downstream) may rise too slowly. If I am reading things right, this is saying really lean. Lambda sensors produce a voltage signal that recognises the amount of unburnt oxygen in the exhaust. If it is jumpy between 0. Testing Oxygen Sensor In Jeep Liberty » This is images about testing oxygen sensor in jeep liberty posted by Maria Nieto in Testing category on Oct 12, 2019. I wrote up a thread on that since the drivers side sensor is a bit of a challenge to get to to say the least. 8 V8 85k miles. If the post cat O2 sensor's voltage fluctuates too rapidly (like the pre-cat O2 sensors are supposed to), that triggers the P0420. The voltage should go initial lean (positive voltage) and then rich (negative voltage) as it responds to the exhaust Oxygen content. Using your multimeter, you need to make sure that there’s continuity between PIN 1 and your chassis ground, and PIN 3 and the ground. To test the rear O2 sensor the computer will force a rich or lean mixture that the catalytic converter can't compensate for and then monitors the HO2S voltage. A good sensor will oscillate from below 0. com for not much more than $200. That large peak on the blue line for the upstream sensor is an indication of a misfire. The post cat sensor should also respond every second but should be fairly stable in output voltage Your 2nd run waveforms with precat sensor disconnected looks normal as the downstream post cat sensor, realising there's no upstream O2 sensor output, tries to wake up the sensor by giving it some rich to think about. I'm getting an intermittent P013C code for passenger side downstream O2 sensor slow to respond rich-lean. 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. My 2005 Buick LaCrosse runs smooth. Backprobe the other heater wire, sensor plugged in, and take a voltage reading. The second downstream oxygen sensor showed a fault of no signal voltage from the downstream O2 sensor, and good signal voltage from first O2 sensor when looking at OBD software. Your o2 in the cat is there to tell the ecu how the cat is performing and if its doing its job. The fuel control module 208 may operate in the pseudo-open-loop state when more than one O2 sensor is disposed downstream from the engine 12 and one of the O2 sensors is not faulty. The downstream sensor usually has no impact on fuel trim like the upstream ones. I may have a pin hole leak downstream of the rear sensor but I am asking if that outside air could reach the o2 sensor would there be voltage dithering or would it just peg to rich? Pretty sure it would peg high in the v range. The readings for the front the sensor 1, sensors look normal. 5 ‘Drive train’ means the part of the powertrain downstream of the output of the propulsion unit(s) that consists if applicable of the torque converter clutches, the transmission and its control, either a drive shaft or belt drive or chain drive, the differentials, the final drive and the driven wheel tyre (radius);. In the graph at right, the downstream oxygen sensor voltage stabilizes at about. png i suspect that's when you drivelink this system and graph the lambda sensor and not what you will. 2 volts to above 0. The o2 sensors are very important for the proper operation of the engine. When you do a rapid throttle snap the engine runs lean for a brief moment during the gulp of air that fills the vacuum in the intake manifold (PCM and injectors can't deliver a burst of fuel that fast). The downstream sensor is exposed to less punishment, and may be better. Should the front O2 sesnor ever be as high as 1. Kinda gotta figure a downstream O2 sensor is a downstream O2 sensor. I replaced post cat O2 sensor to new Denso O2 sensor. PO132 is Oxygen Sensor Voltage High bank 1. When the fuel mixture is rich (less oxygen in the exhaust), the sensor's output jumps up to a high of about 0. Two upstream sensors (between the exhaust manifold and catalytic converter) and Two downstream (between the catalytic converter and muffler). 78 but would occasionally drop to. - O2 sensor 2 (Is this downstream?) was quite stable around 0. 1 sensor, bank 1 sensor 1 and the downstream sensor should be a relative flat line right at. 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. The attached graphs represent O2 voltage output at 35 MPH and 55 MPH respectively. takes maybe 30 minutes. Focus on the downstream O2 voltage output. Check out our starter guide here. 9 volts when the air/fuel mixture is rich, then drops to 0. A voltage is applied to the pump cell diffusion gap to maintain a constant sensing l 1 air fuel ratio through extreme rich and lean conditions. A p0420 is a catalyst efficiency fault. I think the O2 voltage graph on yours shows something wrong. Scroll to Bank 1 Sensor 2 and take a look at the voltage. The tip of the sensor has a zirconium ceramic bulb coated on the inside and outside with porous platinum, which serve as the electrodes. Also, having a "lazy" downstream sensor has the opposite effect as a lazy upstream one, making Cat Mon pass a bad catalyst. Downstream O2 sensor voltage drops durring acceleration Normal? was created by Drunken Elvis 2. note standard O2 sensor socket is difficult to fit in the space and the strain relief on the OE part doesn't bend too well in the socket. My advice is to maintain your focus on how to diagnose these sensors in. The ECM uses the signal from the front and the rear oxygen sensors to control the engine operation and to monitor the performance of the catalytic converter, which is a major part of the vehicle's. Therefore, the downstream oxygen sensor (sensor 2) should produce a steady voltage of approximately 0. A basic DIY scan tool will typically sell for $50 to $200, with higher priced tools offering greater capabilities. Step One Install the Wideband O2 Sensor. It slightly richens the mixture to make the cat heat up faster, and it leans it a bit if the cat gets too hot. I unplugged the pre-cat sensor and the graph flatlined at 18000. The ECM then compares the readings of the two O2 sensors to determine if the converter is functioning within set parameters. Sensor 1 is a planar dual-cell limit current sensor and is designed to output a near constant voltage of 1. In this manner, the downstream oxygen (sensor 2) should create a relentless voltage of roughly 0. temperature sensor can also prevent the system from going into closed loop. I'll be posting the graph for refrance shortly and how to take the connector apart so you don't have to hack the wires to install this thing. Ranger & B-Series - O2 sensors Planar or Thimble - I have a 2004 Ford Ranger with 4. A switching voltage on the post-cat sensor indicates that the gases are passing across the catalytic converter's ceramic monolith without being subjected to chemical change and therefore the cat requires replacing with a known good unit, providing that the pre-cat waveform is within specification. However, I see my downstream sensor for Bank 2 (Bank 2 Sensor 2) is stable at 0. 1V (downstream is 0. These are P1120, P0151, P1151 and P0174. So instead of just telling the ECU that the motor is running rich, it will read a. The P0420 and P0430 codes are set by the ECM using the downstream or secondary O2 Sensor. When I cut throttle Both o2 sensors went to 0. Hook up the voltmeter's red probe to the sensor's signal wire and the black probe to engine ground. Downstream Heated Oxygen Sensor Heater Failure. Hi, I have a 2002 2. –– The O2 sensor upstream of catalyst (closest to engine) has suffix x1 while O2 sensor downstream of catalyst has suffix x2. As stated, it might be the downstream O2 sensor. HOWEVER, the downstream, although new, did endure a lot of coolant when the motor blew. slower is better on rear sensors. In the voltage graph above, the engine is warming up and the upstream oxygen sensor (top) begins sending a switching voltage signal to the PCM. I didn't believe so I double checked by actually connecting to the pins in the ECM as described by the Toyota service manual. Still O2 sensor output voltage stuck to 0. If that's what has happened, it will be very obvious if you watch a graph of the "O2 sensor voltage" on the "bank 1 sensor 2. The next day I had to go back, because they didn't change the sensor, which they did for free. 21: Downstream Heated Oxygen Sensor Stays at Center. 9 volts) for more than 10 seconds indicating a lack of oxygen in the exhaust stream and an abundance of fuel at sensor 2 on bank 2 of the engine. The oxygen sensor is designed to operate within a particular range, if this range is exceeded the sensor will give the appearance that it has failed. One wire sensors employ only a signal wire, while two wire versions also have a wire going to ground. When the engine is first started, the downstream O2 sensor's output will mirror that of the upstream O2 sensor, and flip-flop back and forth between rich and lean. So the upstream sensor voltage should switch with mixture changes, but the downstream sensor voltage should be fairly steady. It's best to order the correct part using your VIN number. So, I guess on level 3 the ECU ignores the o2 sensors. I have the same code in my 2004 Accord, P0137 $09 O2 Sensor Circuit Low Voltage - Bank 1 Sensor 2. 7L GM vehicle is not that hard to do. There is a slight possibility of a minor exhaust leak 12 inches after of the second O2 sensor. I then started looking at the injector data and plotted some stuff in excel. STFT (short term fuel trim) is the instantaneous response of the ECU to reduce or add fuel to maintain an ideal combustion mixture. Automotive Sensor Testing and Oscilloscope Waveform Analysis goes deep into explaining how most vehicle sensor work and how to test them. Oxygen Sensor Locations. Nissan Micra K11 2001 coilpack - Failed Mot on emissions - natural idle CO only. Diverse parameters as pH, temperature, oxidation-reduction potential (ORP. To evaluate the health of the sensor and confirm the diagnosis, we observed the sensor voltage while accelerating and decelerating. 8v 2) the sensor has the proper resistance 3)the sensor is getting enough power i. If the downstream O2 sensor reading is fluctuating from high to low like the front sensor, it means the converter is not functioning. PassFail Instructor Signature 6 Use scope and graph the o2 heater 5 pts from GMT 1100 at Ranken Technical College. Well, after putting it all back together it no longer throws the code although the drivers side downstream O2 sensor shows. The sensor produces a voltage that changes when the amount of unburned oxygen in the exhaust changes. That's not right. The post cat sensor should also respond every second but should be fairly stable in output voltage Your 2nd run waveforms with precat sensor disconnected looks normal as the downstream post cat sensor, realising there's no upstream O2 sensor output, tries to wake up the sensor by giving it some rich to think about. The OBD II system can't evaluate the converter if the upstream and downstream O2 sensors are not functioning normally. Hi, I have a 2002 2. Your car is being desperate to get the rich feed that the downstream O2 sensor is usually supposed to feed to the computer. The O2 closest to the engine ahead of the cat is Sensor-1. You can also find other images like images wiring diagram, images parts diagram, images replacement parts, images electrical diagram, images repair manuals, images engine diagram, images engine scheme diagram, images wiring harness diagram. An O2 sensor stuck at a fixed bias voltage is a sign of an open O2 sensor circuit or dedicated ground. HOW THE O2 SENSOR WORKS The O2 sensor used in most vehicles is a voltage generating sensor. If it is jumpy between 0. note standard O2 sensor socket is difficult to fit in the space and the strain relief on the OE part doesn't bend too well in the socket. If you open the captures in a picture viewer, you can zoom in and examine each of the traces more closely than you can here in the forum. Exhaust exiting the cat I would think would have no oxygen in the stream and in that condition, the front O2 sensors would report a value closer to 1v rather than 0v. The distillation apparatus has a resolution almost twice as good as D86 distillation units, yielding results that are well within ASTM D86 r/R requirements. its very poor on mpg currently only getting around 15. They are heated by the exhaust flow whether or not O2 is enabled in the ECU. Changed Both Upstream and downstream O2 sensors - Answered by a verified Nissan Mechanic. If available, the factory O2 sensor location is usually preferable. Test for O2 sensors behind the catalytic converter: Graph the rear and the front O2 sensor output. When the engine stalls we have good voltage and ground @ the pump connector on the tank, tach reference and spark are good. High sensor. You should see the voltage varying during acceleration and then stabilize. 1v) when lean and pulls it high (0. The ECU would add more fuel and get a rich voltage back rom the sensor,except the ECU is programmed to read high voltage as lean, even though the sensor was responding as it should. For wide-band O2 sensors and linear O2 sensors, the value may be higher, or it may be converted to a zero to one volt scale. Replacing an air fuel ratio sensor costs $65-$320 part plus $50-$150 labor. The graphs of downstream O2 sensors also look more consistent than what you're seeing, which could be from the upstream sensor going sideways. If you were to graph the voltage, it would be pretty much a straight line. This is with me holding a constant throttle position and a constant RPM. If the voltage of the second O2 sensor bounce up immediately after resuming normal driving, the catalytic converter is likely bad. 2 litre 06 Chevrolet/220,000 miles, has had a P0420 code come and go twice in the last few weeks. Also check if your sensors like cat evap o2 and ho2 say ready. Under 2000 rpm's the wide-range sensor goes all over the place rich-lean and the other sensor acts like it should for a downstream sensor, fluctuating slowly and consistently, just the voltages seem wonky. So, I started the engine and watched how much time dows it take for the O2 sensor to produce usable voltage: maybe after 20. It looks like both your sensors are operating correctly. Below are the recorded graphs while I was driving with new O2 sensor. Well your front o2 sensor is there to work with air/fuel ratio and should range from about 0. This code is triggered by the first downstream (front) O2 sensor. Therefore, the downstream oxygen sensor (sensor 2) should produce a steady voltage of approximately 0. the ECU is getting no input whatsoever, i. The downstream O2 sensor voltage is pretty steady, but usually below 0. Also, why is there no value for "02 volts Bank 1 Sensor 1"? I ran a graph of live data and it shows pretty much the same. He is certain that he had no problems before the dealer did the 12k service, so maybe a bent pin, pinched wire or just an odd coincidence. 9 volts correct?. Less than 0. If the downstream O2 sensor reading is fluctuating from high to low like the front sensor, it means the converter is not functioning. But, my downstream/bottom O2 sensors sensor 2 bank 1 and bank 2 are reading between 0. To illustrate, a misfire caused by a lean A/F mixture will drive the downstream voltage lower because an excess of oxygen is passing through the catalytic converter. Someone please explain the O2 closed loop bias voltage to me So I understand how the O2 circuit works, the ECU injects a high impedance voltage and the O2 sensor then sinks it low (0. Sensor Guide software Covers Engine Sensor Operation and Diagnosis Onboard Diagnostics (OBD2)Guide software Basics of OBD II Emission Guide software Basics of Emissions Diagnosis and Repair Wheel Alignment & Suspension Diagnosis Guide software Basics of Wheel Alignment, Steering and Suspension. Hi Roland, I did two days of scanning on the car. 9v) when rich. 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. As for O2 Sensor Bank 1 Sensor 2 (downstream), it is also fluctuating all over seeming to replicate Sensor 1 but slightly delayed. Inside the vented cover on the end of the sensor that screws into the exhaust manifold is a zirconium ceramic bulb. As far as the fuel injectors go. Once the converter lights off, the downstream O2 sensor will settle down and "flat-line" at a steady voltage reading usually around 0. If you have continuity, sensor wire is properly grounded. Engine Misfire and Fuel Trim Analysis Techniques. The sensor's voltage reading should also be fairly steady (not changing up or down), and average 0. 5:1 AFR required for maximum power can give O2 voltage from 0. In the graph at right, the downstream oxygen sensor voltage stabilizes at about. Let me clarify some mistruths here. The upstream O2 sensor switched rapidly between -0. While both banks show the #1 sensor very similar, the Bank 2 Sensor 2 graph is vastly different from the B1S2 graph. The ho2 sensor informs the ecm that the post-twc air-fuel ratio is lean (low voltage, i. A defective cat won't throw a code like this; a bad cat's downstream O2 sensor output graph will match the upstream O2 sensor's graph more or less on a 1:1 stepping (meaning as the upstream voltage goes up so too will the downstream O2 sensor, and, vice-versa so that you get nearly. For this reason, the techniques used to test and diagnose the regular Zirconium O2 sensor can not be used to test the wide-band AFR sensor. Does it really matter if it is bank 1 or bank 2? Could not say for sure one way or the other. It slightly richens the mixture to make the cat heat up faster, and it leans it a bit if the cat gets too hot. 5v where it is connected. If all the wiring looks good then reset the ECU and see if the code comes.