All 4 O2 Sensor Failure

Liv'n Life

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Original poster
Joined
Dec 3, 2021
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15
Location
North Carolina
Ok, I have read through several threads on this and tried many of the suggestions to no success. CEL came on. Codes indicate that all 4 O2 sensors are bad, however they were literally just replaced last year with NTK's, along with the exhaust system.

2004 LJ / automatic

Here is what I have tried:

- Checked ground from block to firewall
- Checked wires for the sensors
- Broke down and bought 4 new sensors (NTK)
- Had a spare PCM - tried that

The pre-cats and cat were replaced last year (along with all 4 O2 sensors). Probably less than 3k miles ago.

I am at a complete loss at this point... any suggestions much appreciated.
 
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Reactions: Wranglerfix
NTK's both times (as recommended by most everyone on this site). They worked fine for about a year with no issues. I don't think it's the sensors but we replaced them again (with NTK's) and still have codes. Something weird is going on.

I think you need to look close at your wiring harness- And maybe even get @Wranglerfix in the equation- All four of those are not just going to fail at one time.