O2 sensor 1 bank 2 reading zero, code P0135

QEWANI

MEMBER
2000 LEXUS LS 400
4.0L
V8
2WD
AUTOMATIC
500,000 MILES

I tried swapping the sensor from bank 1 sensor 1 and it reads properly on bank 1, in bank 2 it reads for first drive after the swap but later it only reads zero. I am getting code P0135 tried clearing it and it comes again. For me the sensor seems fine but no idea why it reads zero on bank 2. What could be wrong?

11 Replies

KEN

ADMIN

Hello,

This could be a connection problem between the PCM and sensor. Here is a guide so you can check the connections and the engine oxygen sensor wiring diagrams so you can see how the system works and the wires that need to be checked:

https://www.2carpros.com/articles/how-to-check-wiring

Check out the diagrams (below). Please let us know what you find. We are interested to see what it is.

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Saturday, October 19th, 2019 AT 3:58 PM

QEWANI

MEMBER

Bank 2 seems having a leak or something, on idle I have noticed that, the STFT on bank 2 reads 19 and O2B1 pre cat reads zero and O2B1 post cat read 9 volts. But with pressing full throttle for seconds the STFT drops to normal 0 to 10, and O2B1 pre cat starts fluctuates between 0.7 to 0 volts and O2B1 post cat drops to zero volts, but when releasing the throttle all returns to same old readings.

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Sunday, October 20th, 2019 AT 9:18 AM

KEN

ADMIN

An exhaust leak can cause this issue because it allows air into the exhaust system causing the readings to go to 0. We should repair the leak first. Can you please shoot a quick video with your phone so we can see what's going on? That would be great. You can upload it here with your response. That way I can tell if the noise is bad enough to cause the problem.

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Sunday, October 20th, 2019 AT 11:55 AM

QEWANI

MEMBER

First 2 videos car on idle and pressing full throttle for seconds.

Third video with car driving, the O2B2 sensor one reading but still very low.

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Monday, October 21st, 2019 AT 11:06 PM

KEN

ADMIN

Thanks for the videos. On the first one the O2 sensors are not going to do much when the engine is cold and in closed loop. The bank 2 sensor is flat for sure. I didn't hear too much of an exhaust leak did you fix it or? If the wiring is okay (I would double check it) the PCM is bad. The engine seems to run okay? Get a used/rebuilt unit) Check out the diagrams (below). Please let us know what happens.

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Tuesday, October 22nd, 2019 AT 11:40 AM

QEWANI

MEMBER

Will a Japanese PCM will work on american spec car?
Why should I change the PCM?

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Tuesday, October 22nd, 2019 AT 11:12 PM

KEN

ADMIN

If the wiring is good and you changed the sensor and the engine is running okay the PCM cannot monitor the sensor so it must be replaced. The part numbers must match.

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Wednesday, October 23rd, 2019 AT 11:35 AM

QEWANI

MEMBER

In the diagram you posted it shows ECM unit that is PCM right? Will get it changed since the car has 500,000 miles it seems the PCM is bad, really since I cannot reset ABS codes anymore as I used to do before with TC and E1 connected with a pin and depressing brake pedal, currently am getting one code only, will change PCM and report back.

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Saturday, November 9th, 2019 AT 2:36 AM

KEN

ADMIN

Sounds good, please let us know.

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Saturday, November 9th, 2019 AT 11:21 AM

QEWANI

MEMBER

I have changed the ECU with a used ECU, first video showing sensor is reading voltages but after few minutes in video 2 you can see that again its still reading zero. So what is next? Shall I return the ECU and reuse my old ECU? I will get my money refund! What to check next?

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Tuesday, November 26th, 2019 AT 9:58 AM

KEN

ADMIN

Maybe we are barking up the wrong tree. An oxygen sensor will not switch if the mixture cannot be controlled. O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 1) ... Code P0135 occurs when the sensor needs to be replaced, have you done this? Here is a guide to help:

https://www.2carpros.com/articles/how-to-replace-an-oxygen-sensor

Also I have seen the MAF sensor cause this issue here is the location so you can check it out. Check out the diagrams (below). Please let us know what you find.

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