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Does This O2 Sensor Look Like Trouble?

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YOUR RESEARCHDoes This O2 Sensor Look Like Trouble?

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Replace back

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Unsuccessful attempts: 1
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Performed · outcome unconfirmed · Original poster
I just swapped back to my Fabspeed X-pipe and noticed one of the oxygen sensors (bank 1, primary) was black while all the others were white/gray.
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Does This O2 Sensor Look Like Trouble?

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Leading evidence: 'Replace back' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Replace back' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.

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Replace few weeks ago

Performed · outcome unconfirmed

No successful repair reported for this finding.

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Reported fixes: 0
Unsuccessful attempts: 1
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Performed · outcome unconfirmed
FWIW, here are my four original O2 sensors that I replaced a few weeks ago.
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Does This O2 Sensor Look Like Trouble?

Frequently discussed actions (2)

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Replace back

No successful repair reported for this finding.

0
Reported fixes: 0
Unsuccessful attempts: 1
Discussions

Read evidence and context

Discussions that performed work without a confirmed outcome: 1

0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.

0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.

Performed · outcome unconfirmed · Original poster
I just swapped back to my Fabspeed X-pipe and noticed one of the oxygen sensors (bank 1, primary) was black while all the others were white/gray.
Original post Read captured discussion
Does This O2 Sensor Look Like Trouble?

Replace few weeks ago

No successful repair reported for this finding.

0
Reported fixes: 0
Unsuccessful attempts: 1
Discussions

Read evidence and context

Discussions that performed work without a confirmed outcome: 1

0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.

0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.

Performed · outcome unconfirmed
FWIW, here are my four original O2 sensors that I replaced a few weeks ago.
Original post Read captured discussion
Does This O2 Sensor Look Like Trouble?

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5 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.

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Generation: 20261027T044418Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources

POST 1 / ORIGINAL POSTEROriginal post

I just swapped back to my Fabspeed X-pipe and noticed one of the oxygen sensors (bank 1, primary) was black while all the others were white/gray. This is on my recently rebuilt 3.8L w/ Nickies and JE pistons with about 1,000 miles on it. Any chance this correlates with a recent P0491 and P0492 code?

POST 2Original post

They all look a bit crappy to me. Typically they have a light greyish coating. The black one indicates a very rich mixture and the others look they aren't far off. If these were new with the engine rebuild, I'd want to take a good look over everything to make sure you aren't dumping fuel for some reason. Shouldn't be related to your SAI code unless the 02s are so worn that they aren't reading the extra oxygen when the SAI pump comes on.

POST 3 / ORIGINAL POSTEROriginal post

Quotes source post: 17391591

Thanks for the reply. The sensors are not new. I feared that one bank might be experiencing a rich mixture. I have new injectors. How would you go about diagnosing why I'm running rich? Any advice is appreciated.

POST 4Original post

Quotes source post: 17391591

I agree, something seems off. FWIW, here are my four original O2 sensors that I replaced a few weeks ago. Car had 40k miles when they were removed. The two on the right are the post-cat sensors and the two on the left, pre-cat ('99 C2).

POST 5 / ORIGINAL POSTEROriginal post

Wow - that's a big difference. Makes me even more curious now. I wonder if the fact that you have 40K on yours (assuming with the same enginne) and mine are with a rebuild that doesn't have the rings as seated. I can tell you that I replaced the bad one today and now my Long Term Trim levels for both banks are at 0%. Seems odd that both would be affected since just one O2 sensor was replaced, but maybe just one bad sensor can throw everything off.

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