23 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHF/S Fabsped Cat Bypass Pipes
Reported or suspected cause
high measuring threshold between the pre & post sensor
Reported cause
No successful repair reported for this finding.
1
Identified cause
0
Suspected cause
0
Reported fixes
Read evidence and context
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 report identifying a cause
1
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0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Reported cause
This is due to a high measuring threshold between the Pre & Post Sensor.
Leading evidence: 'high measuring threshold between the pre & post sensor' (1 discussions report identifying this cause; no attributable repair resolution). Across 1 matching discussions, the most frequently mentioned possible cause is 'high measuring threshold between the pre & post sensor' (1 discussions; 1 report identifying it and 0 suggest it). The most frequently discussed action is 'Run bypass pipes besides smog and possible cel's' (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.
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
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Suggestion
so what are the negatives to running the bypass pipes besides smog and possible cel's?
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
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Suggestion
Ed did you run mufflers with these bi-pass pipes and what are you going to now?....
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
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Suggestion
I am retiring my 996 to street use and have a set coming off my car between now and January.
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
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Suggestion
with those using mufflers with them, do they increase exhaust volume significantly?
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.
23 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: 20261026T172408Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
996 X51, race car, 100 octane. No idea why. Maybe the CEL comes into play during extended idling, low load driving? I believe during full throttle, the engine is mostly closed loop?
If you put in an O2 sensor spacer on the 2ndary sensors you won't ever see the CEL due to the bypass pipes. Pretty standard technique for nearly any car out there.
I had read a technical article somewhere that the Mrk1 996's (up to MY02) will not experience the CEL from cat bypass pipes. This is due to a high measuring threshold between the Pre & Post Sensor. If you do trigger the CEL you can have it reflashed to RoW that will eliminate the Secondary O2 sensors in the loop.
so what are the negatives to running the bypass pipes besides smog and possible cel's?
with those using mufflers with them, do they increase exhaust volume significantly?
A friend runs his track (DE) car w/o Cats, combined with FBL headers & Mufflers ( after he keep blowing the 100 cel cats to shreds). At idle it is no louder then my car with 200 Cel Cats & No Mufflers. On the track his is substantially quiter then my car at WOT.
Hey guys,
Let me throw my hat in the ring too, I've got a set of muffler bypass pipes for a 996 C4S.
They've been used ones but look a little rough around the edge, if anyone is interested make me an offer.
FYI, with these you don't have the check engine light issue but I've got to warn you they are LOUD.
Sid.
