Porsche Club GB

996 C4S high emissions problems

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

THIS DISCUSSION / SOURCE-DERIVED OVERVIEW

Discussion summary

YOUR RESEARCH996 C4S high emissions problems

Leading reported evidence

Replace o2 sensors, the air/oil breather box, no help

Performed · outcome unconfirmed

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 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
changed o2 sensors, the air/oil breather box, no help.
Original post Read captured discussion
996 C4S high emissions problems

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Leading evidence: 'Replace o2 sensors, the air/oil breather box, no help' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Replace o2 sensors, the air/oil breather box, no help' (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.

Source reports, not a diagnosis or a success probability. Counts refer to discussions and can overlap.

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1 matching discussions · 3 captured posts examined · 0 partial discussions

Compare 1 other evidence results

Run some porsche-specific diagnostics

Suggestion or failed attempt

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
Has your specialist run some Porsche-specific diagnostics to see if any errors are flagged-up?
Original post Read captured discussion
996 C4S high emissions problems

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.

Replace o2 sensors, the air/oil breather box, no help

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
changed o2 sensors, the air/oil breather box, no help.
Original post Read captured discussion
996 C4S high emissions problems

Run some porsche-specific diagnostics

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
Has your specialist run some Porsche-specific diagnostics to see if any errors are flagged-up?
Original post Read captured discussion
996 C4S high emissions problems

Coverage and how to read this overview

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.

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

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

POST 1 / ORIGINAL POSTEROriginal post

Morning, my car is at a specialist garage and we are struggling with a issue of the emissions being high at 4% co on both banks. drives well, no smoke etc changed o2 sensors, the air/oil breather box, no help. exhaust is old but seems ok, Cats again old but look ok inside etc. the odd issue is if you take the oil cap off the emissions improve ….. confused !!!!!

POST 2Original post

Hi Stuart, By changing the lambda sensors and the air-oil separator you’ve covered a couple of potential sources of your problem, although there still could be something amiss with the recirculation system [a faulty valve maybe?]. Brand new AOSs have been known to be faulty … a good check is to see if the oil filler cap is difficult to remove when the engine is idling. Maybe there’s a MAF or fuel injection system issue? Has your specialist run some Porsche-specific diagnostics to see if any errors are flagged-up? Jeff

POST 3 / ORIGINAL POSTEROriginal post

Thanks Jeff i will ask the question. I’m starting to wonder if the car has been Mapped before I brought it…

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