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o2 sensor exhaust problem


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bayview512
New User

Sep 17, 2023, 9:33 AM

Post #1 of 4 (34900 views)
o2 sensor exhaust problem Sign In

i have a 2007 jeep liberty and the engine light came on. after testing the error showed o2 sensor bank 1 sensor 2 was bad. i changed both banks 1 and 2 sensors 2. after driving a few minutes, engine light cam back on, the obc readout showed codes p138 and 158 which were now high voltage on both new sensors. so it seems the sensors are now good so what should i be looking at since there appears to be a rich fuel problem.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Sep 17, 2023, 11:23 AM

Post #2 of 4 (34893 views)
Re: o2 sensor exhaust problem Sign In

The first thing you need to learn is that there are NO codes that confirm a part is bad. They merely inform you of a condition that needs to be further troubleshooted. There are dozens of 0/2 related codes that all mean something different.
The dead giveaway on this one is that both rear sensors are setting the same code. You are also wrong about it being a rich condition also as fuel mixture and control are done by the front sensors. The rear sensor are for Cat monitors only.

In this case you have a short to power on the signal lines which could be a problem with the wiring harness or the PCM itself. It definitely requires some in depth electrical testing to locate the cause.

I would start by simply inspecting the harness closely looking for anywhere it could have been burned on the exhaust or somehow otherwise damaged.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



bayview512
New User

Sep 18, 2023, 7:17 AM

Post #3 of 4 (34843 views)
Re: o2 sensor exhaust problem Sign In

thankyou for your feedback


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Sep 18, 2023, 7:19 AM

Post #4 of 4 (34840 views)
Re: o2 sensor exhaust problem Sign In

You're welcome



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.







 
 
 






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