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Intermittent crank-no start - 986 Forum - The Community for Porsche Boxster & Cayman Owners

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YOUR RESEARCHIntermittent crank-no start - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Leading reported evidence

Replace cps (a used one

Performed · outcome unconfirmed

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Reported fixes: 0
Unsuccessful attempts: 1
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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

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Performed · outcome unconfirmed
I changed the CPS (a used one from another engine) and so far so good after a couple of test drives.
Original post Read captured discussion
Intermittent crank-no start - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Frequently discussed work

Check other than

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Unsuccessful attempts: 1
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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 · Original poster
Is there anything else I can do to check other than replacing the part?
Original post Read captured discussion
Intermittent crank-no start - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Read full discussion summary

Leading evidence: 'Replace cps (a used one' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Check other than' (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 · 5 captured posts examined · 0 partial discussions

Compare 4 other evidence results

Check other than

Suggestion or failed attempt

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Reported fixes: 0
Unsuccessful attempts: 1
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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.

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

Suggestion · Original poster
Is there anything else I can do to check other than replacing the part?
Original post Read captured discussion
Intermittent crank-no start - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Replace can be done

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.

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

Suggestion
The CPS is easy to change, can be done on jack stands -- its a bit of a blind access, but it's one bolt and
Original post Read captured discussion
Intermittent crank-no start - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Replace cps-crank-position-sensor-jackstands.html#post657480

Suggestion or failed attempt

No successful repair reported for this finding.

0
Reported fixes: 0
Unsuccessful attempts: 1
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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.

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

Suggestion
http://986forum.com/forums/performance-technical-chat/84177-changing-cps-crank-position-sensor-jackstands.html#post657480
Original post Read captured discussion
Intermittent crank-no start - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Replace sensor - even if it turns out

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.

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

Suggestion
I’d just go ahead and replace the sensor - even if it turns out to be something else, they are known to fail so a fresh one will benefit you down the line anyway.
Original post Read captured discussion
Intermittent crank-no start - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Frequently discussed actions (8)

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

Check other than

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 · Original poster
Is there anything else I can do to check other than replacing the part?
Original post Read captured discussion
Intermittent crank-no start - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Replace can be done

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
The CPS is easy to change, can be done on jack stands -- its a bit of a blind access, but it's one bolt and
Original post Read captured discussion
Intermittent crank-no start - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Replace cps (a used one

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
I changed the CPS (a used one from another engine) and so far so good after a couple of test drives.
Original post Read captured discussion
Intermittent crank-no start - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Replace cps-crank-position-sensor-jackstands.html#post657480

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
http://986forum.com/forums/performance-technical-chat/84177-changing-cps-crank-position-sensor-jackstands.html#post657480
Original post Read captured discussion
Intermittent crank-no start - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Replace sensor - even if it turns out

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
I’d just go ahead and replace the sensor - even if it turns out to be something else, they are known to fail so a fresh one will benefit you down the line anyway.
Original post Read captured discussion
Intermittent crank-no start - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Test drives

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
I changed the CPS (a used one from another engine) and so far so good after a couple of test drives.
Original post Read captured discussion
Intermittent crank-no start - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Test would be

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
The only way to test would be to use an oscilloscope of some description while the fault is evident.
Original post Read captured discussion
Intermittent crank-no start - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Use oscilloscope of some description while the fault is evident

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
The only way to test would be to use an oscilloscope of some description while the fault is evident.
Original post Read captured discussion
Intermittent crank-no start - 986 Forum - The Community for Porsche Boxster & Cayman Owners

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.

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

986Forum: 1 discussions

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

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

Outcome without a verified action link
I bypassed the fuel pump relay with no change.
Original post Read captured discussion
No unique explicit quoted action; no causal link assigned

Generation: 20261026T163944Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources

POST 1 / ORIGINAL POSTEROriginal post

Hi there, 986S which has intermittently been not starting. This seems to happen only when it is warm. After I come back a few hours later the car starts again. The tach moves slight when I turn the key to on position (regardless of whether it starts or not) — ie up to 0 rpm. I bypassed the fuel pump relay with no change. The fuel pump sounds like it is coming on. No CEL. When I crank the engine and the car DOES start I see a subsequent tach bounce initially (eg up to around 200ish and then it goes to 1000rpm on ignition). When I crank and does NOT start I see no tach bounce. If I understand correctly, this is what a CPS fail looks like? Is there anything else I can do to check other than replacing the part?

POST 2Original post

The symptoms match a Crank angle sensor fault. The only way to test would be to use an oscilloscope of some description while the fault is evident. I’d just go ahead and replace the sensor - even if it turns out to be something else, they are known to fail so a fresh one will benefit you down the line anyway.

POST 3Original post

I have not had this issue personally. But if I remember correctly from previous posts, if the crank position sensor is bad, the tach won't move while cranking.

POST 4Original post

The CPS is easy to change, can be done on jack stands -- its a bit of a blind access, but it's one bolt and not too hard to get at once you find it. just be sure to put a shop towel in the hole underneath the CPS, please don't ask why I know this to be important :-) Mike

POST 5Original post

Quotes source post: 594212

I have been having the same symptoms, "intermittently ... not starting. This seems to happen only when it is warm. After I come back a few hours later the car starts again." I changed the CPS (a used one from another engine) and so far so good after a couple of test drives. I created a thread with some helpful tips from my experience. http://986forum.com/forums/performance-technical-chat/84177-changing-cps-crank-position-sensor-jackstands.html#post657480

This is a source reference. Confirm exact model applicability in the original material.