Carpokes

O2 sensor warning

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5 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis

THIS DISCUSSION / SOURCE-DERIVED OVERVIEW

Discussion summary

YOUR RESEARCHO2 sensor warning

Leading reported evidence

Install ultimate aos, and signal seems more frequent

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Performed · outcome unconfirmed · Original poster
BTW, recently installed Ultimate AOS, and signal seems more frequent.
Original post Read captured discussion
O2 sensor warning

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Leading evidence: 'Install ultimate aos, and signal seems more frequent' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Install ultimate aos, and signal seems more frequent' (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 & have increased mpg

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Performed · outcome unconfirmed
Replaced all & have increased mpg.
Original post Read captured discussion
O2 sensor warning

Replace four or just the ones throwing codes

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Suggestion
Would you replace all four or just the ones throwing codes?
Original post Read captured discussion
O2 sensor warning

Replace sensors is pretty reasonable, especially if they’re original

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Suggestion
Yeah, at 78k on the exhaust I’d say replacing the sensors is pretty reasonable, especially if they’re original.
Original post Read captured discussion
O2 sensor warning

Frequently discussed actions (4)

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Install ultimate aos, and signal seems more frequent

No successful repair reported for this finding.

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Reported fixes: 0
Unsuccessful attempts: 1
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Discussions that performed work without a confirmed outcome: 1

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Performed · outcome unconfirmed · Original poster
BTW, recently installed Ultimate AOS, and signal seems more frequent.
Original post Read captured discussion
O2 sensor warning

Replace & have increased mpg

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
Replaced all & have increased mpg.
Original post Read captured discussion
O2 sensor warning

Replace four or just the ones throwing codes

No successful repair reported for this finding.

0
Reported fixes: 0
Unsuccessful attempts: 1
Discussions

Read evidence and context

Discussions that contain suggestions: 1

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

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Suggestion
Would you replace all four or just the ones throwing codes?
Original post Read captured discussion
O2 sensor warning

Replace sensors is pretty reasonable, especially if they’re original

No successful repair reported for this finding.

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Unsuccessful attempts: 1
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Suggestion
Yeah, at 78k on the exhaust I’d say replacing the sensors is pretty reasonable, especially if they’re original.
Original post Read captured discussion
O2 sensor warning

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

Carpokes: 1 discussions

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Generation: 20261027T005001Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources

POST 1 / ORIGINAL POSTEROriginal post

I get random “check engine” signals (could be every few days or 6 weeks) with O2 sensor fault. No evidence of actual O2 fault, and car runs perfectly. Where should I look for the origin of this signal? BTW, recently installed Ultimate AOS, and signal seems more frequent.

POST 2Original post

What error code are you getting? If it's an O2 sensor-specific code, my guess would be that one or more of your O2 sensors are getting old and sluggish. The car won't necessarily show any noticeable symptoms (poor mileage maybe), but the ECU can detect when the sensors are not reacting as fast as they should. If your sensors are original or haven't been changed in a long time, probably time to change them anyway. It's best to change them all at the same time. Otherwise, the fast new sensor will make the ECU see the other sensors as sluggish and throw the code again.

POST 3 / ORIGINAL POSTEROriginal post

Yep, it’s O2 sensor specific. Engine was built 20k miles ago, but I’m guessing the sensors weren’t touched. At 78k mile on the exhaust system, sensors seem like a good bet. I’ll change them to be safe. Thanks.

POST 4Original post

I had to chuckle at this because my 2000 C2 with 140k had similar issue but the reading said "older O2 sensor". Replaced all & have increased mpg.

POST 5Original post

Yeah, at 78k on the exhaust I’d say replacing the sensors is pretty reasonable, especially if they’re original. I’d still keep an eye on it afterward though, since the increased frequency after the AOS install makes me wonder if there’s a small vacuum or exhaust leak contributing to it. Hopefully the new sensors take care of it and you can forget about the CEL. Would you replace all four or just the ones throwing codes?

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