Lexus is 250 2006 o2 sensor problems

[dgp911]

Had a little incident a few months ago with the local wildlife, took out the rad ,condenser, bottom crossmember and damaged the bumper. All repaired and re MO T ed . Been driving it for a few days and  the engine light/ vsc /traction control light comes on. Scanned for codes and found p0138  o2 sensor bank 1 sensor 2  too high voltage .  Changed the  right hand down stream sensor ,cleared the code and the problem still exists. Swapped  the two downstream sensors over and still the same code.  Looking at the live data , the 2 pre -cat sensors seem to be reading similar to each other. The  bank 1  post cat sensor seems to be  stuck  reading high on tick over and with revs but will drop to zero while coasting.  I'm thinking there's 3 possible causes for this  1 - defective cat   2- 02 sensor or wiring  3 - ecu fault .  The car runs perfect , 35 to the gallon  and there was no faults pre accident.  I've know this car from new  and its been faultless .  Has anyone had similar issues or can anyone advise on a solution 

[Mr Vlad]

Hi David. Bit of a @ummer the accident. Re the error code. I recommend you search within the gen2 IS section of the forum as this subject is unfortunately common. There's quite a bit to read and I suggest you spend a couple hours reading the many threads.

[dgp911]

19 hours ago, dgp911 said:

Had a little incident a few months ago with the local wildlife, took out the rad ,condenser, bottom crossmember and damaged the bumper. All repaired and re MO T ed . Been driving it for a few days and  the engine light/ vsc /traction control light comes on. Scanned for codes and found p0138  o2 sensor bank 1 sensor 2  too high voltage .  Changed the  right hand down stream sensor ,cleared the code and the problem still exists. Swapped  the two downstream sensors over and still the same code.  Looking at the live data , the 2 pre -cat sensors seem to be reading similar to each other. The  bank 1  post cat sensor seems to be  stuck  reading high on tick over and with revs but will drop to zero while coasting.  I'm thinking there's 3 possible causes for this  1 - defective cat   2- 02 sensor or wiring  3 - ecu fault .  The car runs perfect , 35 to the gallon  and there was no faults pre accident.  I've know this car from new  and its been faultless .  Has anyone had similar issues or can anyone advise on a solution 

Can anyone recommend somewhere in the uk to test /repair the ecu

[Linas.P]

5 hours ago, dgp911 said:

Can anyone recommend somewhere in the uk to test /repair the ecu

No. You can only replace it, the good news - it is not very expensive. I got spare for £23, but eventually it got stolen by call-out electrician who said he could programme-out the immobiliser (which at the time was causing issues for me). But that is story for another time.

I tend to think it is wiring issue, rather than ECU issue, if it would be ECU, you are more likely to get all sorts of sporadic problems with various things, not only o2 sensor. As well, if you swapped the sensors and the code remains on bank 1, this is 100% not sensor issue and again in my option points at wiring. 

[dgp911]

Yes , almost sure it’s not a sensor and can’t see it being the cat as it was fine pre accident . Will  see if I can trace wiring back to ecu. 

[Linas.P]

I mean there is slim chance that somehow the accident caused the exhaust leak and sensor is just getting fresh air from leak and thus failing.

[dgp911]

latest update .  Just wired sensor  2 bank 1 into sensor 2 bank 2 plug  to see what the result would be.  Running the car and viewing the live data , the faulty readings seem to have followed to the other bank .    Bank 1 is reading the good bank 2 sensor ok, so I'm  thinking  the problem can't be a wiring or ecu fault . There must be a problem with the bank 1 cat.  The sensor voltage starts low and slowly builds to .85 volts  and stays there . No up and down reading when the  revs are increased . Has anyone got any other ideas or suggestions as to how to test the cat ?.  where's the best place to get a replacement?