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Check Engine Light, error code P0491

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

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YOUR RESEARCHCheck Engine Light, error code P0491

Leading reported evidence

Check airpump

Suggestion or failed attempt

No successful repair reported for this finding.

0
Reported fixes: 0
Unsuccessful attempts: 1
Discussions

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Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.

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
Jim, first check the airpump to see if it turns on when you first start the car.
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Check Engine Light, error code P0491

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Leading evidence: 'Check airpump' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Check airpump' (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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1 matching discussions · 4 captured posts examined · 0 partial discussions

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Check intake/vacuum leaks

Suggestion or failed attempt

No successful repair reported for this finding.

0
Reported fixes: 0
Unsuccessful attempts: 1
Discussions

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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
Someone else may have better advice on checking for vacuum leaks.
Original post Read captured discussion
Check Engine Light, error code P0491

Frequently discussed actions (2)

These are separate views of the same evidence. Frequency alone does not establish a fix, and these counts must not be added together.

Check airpump

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.

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

Suggestion
Jim, first check the airpump to see if it turns on when you first start the car.
Original post Read captured discussion
Check Engine Light, error code P0491

Check intake/vacuum leaks

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.

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

Suggestion
Someone else may have better advice on checking for vacuum leaks.
Original post Read captured discussion
Check Engine Light, error code P0491

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Counts describe captured discussions, not unique people or a diagnosis. Author identities are not reliably stored. Exact duplicate evidence is counted once across matching discussions; one discussion counts at most once per action/state. Multiple repairs reported together remain a combination. Suggestions and failed attempts do not establish a fix. Matches cover whole discussions and can include related faults, model variants and incomplete threads.

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

Rennlist: 1 discussions

0 evidence records excluded for query context · 0 excluded by outcome qualification · 0 adjusted by outcome qualification.

0 acknowledgements have no verified action link; they do not establish a repair result.

Generation: 20261027T075545Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources

POST 1 / ORIGINAL POSTEROriginal post

My car is a 2002 Carrera 4S, 69K miles, I've had it for 1.5 years. Perfect until yesterday, got the P0491 & 492 error codes with CEL. Had the codes read and cleared. Drove again today ~ 15 miles, CEL back on again. I see that the codes are for the secondary air injection system, banks 1 & 2. Any idea how big a deal this is to fix? What would be the likely problem? Any help, please! I'm very nervous about this!

POST 2Original post

Confirm that the pump is working . . .? If you don't know, the pump is located on the top left rear of the motor, by the coolant expansion tank. Confirm that it is working--or not--on start-up. Also, confirm whether the hoses are firmly connected to the pump and the motor. Someone else may have better advice on checking for vacuum leaks. Done any work on the motor lately? Presuming that no other codes come up, this is not a catastrophic event. The SAI is a smog control feature, and is only operable on start-up.

POST 3Original post

Jim, first check the airpump to see if it turns on when you first start the car.

POST 4Original post

https://rennlist.com/forums/996-foru...-with-cel.html Here is a link with information on the SAI

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