Within the last 4 months I have replaced my up and downstream o2 sensors. I am now getting, again an o2 sensor check engine light .. Any suggestions
Why do I keep getting a check engine light for O2 sensors?
- Thread starter G’s Jeep
- Start date
What brand of O2 sensors did you replace them with? If you didn’t use NGK sensors, then that’s your issue.
That makes me feel better I have a NGK coming tomorrow. I never used bosch. I have a denso in my downstream and NGK coming for upstream...Right now I have a champion I believe for upstream. for could there be an exhaust leak? I replaced manifold 4 months ago. Very sure its not manifold.
That’s your issue then. It’s very well known in TJ circles that the only O2 sensors these things like are NGK. Bosch, Champion, and anything else will cause the check engine lights to either not go away, or go on-and-off intermittently.
Either of the two small pre-catalytic converters can cause a false O2 sensor code. My used TJ came with intermittent O2 sensor codes that weren't cured when the previous owner replaced all the O2 sensors with NTKs. One of my two pre-cats finally came apart internally completely clogging the main catalytic converter. Replacing the cats 5-6 years ago cured/stopped all my O2 codes.
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brown_mule
TJ Enthusiast
I had the same problem, I finally replaced my fuel cap after replacing all O2 sensors and the light still coming on! Problem solved!
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Carl McClure
New Member
My O2 sensors are bad, and someone has gutted the Cats. My exhaust guy said to have someone go into the computer and turn off the Cats. It would be $1500.00 to replace all Cats, not including the O2 sensors. If I were to just replace the sensors, he said it would happen again. Any help would be greatly appreciated.
Your exhaust guy isn't aware that what he suggested, reprogram the computer to "turn the cats off" won't happen.
My bad pre-cats caused lots of intermittent false reports of bad O2 sensors. Replacing the pre-cats, admittedly not cheap, stopped all my bad O2 sensor reports. The original O2 sensors were put into the new cats. Those precats are available online for far less than $1500. For example, this set of Walkers that would fit my '04 are only $460. https://www.amazon.com/dp/B00K9Z075O/?tag=wranglerorg-20
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Carl McClure
New Member
Oh cool, yea I'd rather have it done right, and replace the Cats. Thank you so much for the info.
I have a similar check engine light problem with the o2 sensors. I replaced the o2 sensors still check engine light. Took to dealership who diagnosed it as a pcm failure. Waited 4 months for a replacement pcm only to have the same o2 codes come up again. Dealership says thereplacement pcm is bad and has ordered another one. The projected replacement not expected to arrive until Dec. 31!!! Could it be something else besides the pcm? Help, please.
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