986Forum

Random Starting Failure - Help - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Add to repair workspace

New repair projectOpen repair workspace

Original source

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

THIS DISCUSSION / SOURCE-DERIVED OVERVIEW

Discussion summary

YOUR RESEARCHRandom Starting Failure - Help - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Reported repair

Replace cps

Reported resolution

1
Reported fixes: 0
Unsuccessful attempts: 1
Discussions

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 a fix: 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.

Reported fix
Replaced the CPS... problem solved.
Original post Read captured discussion
Random Starting Failure - Help - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Performed · outcome unconfirmed
replaced CPS...
Original post Read captured discussion
Random Starting Failure - Help - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Read full discussion summary

Leading evidence: 'Replace cps' (1 discussions report resolution; 0 report an unsuccessful attempt). Across 1 matching discussions, The most frequently discussed action is 'Replace cps' (1 discussions). For that action, 1 discussions report a resolution and 0 report an unsuccessful attempt. The most frequently reported fix is 'Replace cps', supported by resolution reports in 1 discussions. 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.

Read captured replies

1 matching discussions · 5 captured posts examined · 0 partial discussions

Compare 3 other evidence results

Replace plugs, all coils, crank sensor and fuel filter

Performed · outcome unconfirmed

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
I’ve replaced plugs, all coils, crank sensor and fuel filter.
Original post Read captured discussion
Random Starting Failure - Help - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Run till i shut it off

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
it would start fine when cold and run till I shut it off...
Original post Read captured discussion
Random Starting Failure - Help - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Test cps units is

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
In the end, the best method to test CPS units is with a scope, which quickly shows the problem; cheap parts are often garbage.
Original post Read captured discussion
Random Starting Failure - Help - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Frequently discussed actions (4)

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

Replace cps

1
Reported fixes: 0
Unsuccessful attempts: 1
Discussions

Read evidence and context

Discussions that report a fix: 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.

Reported fix
Replaced the CPS... problem solved.
Original post Read captured discussion
Random Starting Failure - Help - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Performed · outcome unconfirmed
replaced CPS...
Original post Read captured discussion
Random Starting Failure - Help - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Replace plugs, all coils, crank sensor and fuel filter

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
I’ve replaced plugs, all coils, crank sensor and fuel filter.
Original post Read captured discussion
Random Starting Failure - Help - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Run till i shut it off

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
it would start fine when cold and run till I shut it off...
Original post Read captured discussion
Random Starting Failure - Help - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Test cps units is

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
In the end, the best method to test CPS units is with a scope, which quickly shows the problem; cheap parts are often garbage.
Original post Read captured discussion
Random Starting Failure - Help - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Actions with reported resolution accounts (1)

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

Replace cps

1
Reported fixes: 0
Unsuccessful attempts: 1
Discussions

Read evidence and context

Discussions that report a fix: 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.

Reported fix
Replaced the CPS... problem solved.
Original post Read captured discussion
Random Starting Failure - Help - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Performed · outcome unconfirmed
replaced CPS...
Original post Read captured discussion
Random Starting Failure - Help - 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.

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

Generation: 20261027T020439Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources

POST 1 / ORIGINAL POSTEROriginal post

I have a 2001 S with 54k under its belt. Pampered car that’s never missed a service. Randomly, it failures to start. The starter motor spins with great vigour buts there’s no spark. I’ve replaced plugs, all coils, crank sensor and fuel filter. My local specialist has now said it might be that modern fuel is the problem and I should try reddex! Has anyone else had this issue?

POST 2Original post

Quotes source post: 669822

We have seen this when the crank position sensor is going south; the immobilizer in these cars is programmed to shut off the fuel and ignition if the immobilizer does not see the engine turning over, which it gets as a signal from the CPS. This could be a harness problem between the sensor and the immobilizer, causing the intermittent issue.

POST 3 / ORIGINAL POSTEROriginal post

Quotes source post: 669824

Thanks. That makes a lot of sense 👍

POST 4Original post

I have had 2 bad CPCs. One on an engine I bought, engine cranked but no start... replaced CPS... started. The other on a different car was intermittent... it would start fine when cold and run till I shut it off... but would not start when hot. An hour later it would start. Replaced the CPS... problem solved.

POST 5Original post

One of the bigger problems we see all the time is cheap aftermarket CPS that either don't work well or even at all. In the end, the best method to test CPS units is with a scope, which quickly shows the problem; cheap parts are often garbage.

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