fullymatted.
Back to search
Pelican Parts

P0456 Check Engine Light -08 C4 Cabriolet

Add to repair workspace
Open repair workspace
Original source
4 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW

Discussion summary

YOUR RESEARCHP0456 Check Engine Light -08 C4 Cabriolet

Leading reported evidence

Replace gas cap and the light remained

Performed · outcome unconfirmed

No successful repair reported for this finding.

0
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 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 just replaced the gas cap and the light remained on.

Original post Read captured discussion
P0456 Check Engine Light -08 C4 Cabriolet
Frequently discussed work

Check o ring

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

Check the O ring on the cap for cracks.

Original post Read captured discussion
P0456 Check Engine Light -08 C4 Cabriolet
Read full discussion summary

Leading evidence: 'Replace gas cap and the light remained' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Check o ring' (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.

Read captured replies

1 matching discussions · 4 captured posts examined · 0 partial discussions

Compare 4 other evidence results

Check o ring

Suggestion or failed attempt

No successful repair reported for this finding.

0
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 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

Check the O ring on the cap for cracks.

Original post Read captured discussion
P0456 Check Engine Light -08 C4 Cabriolet

Disconnect battery

Suggestion or failed attempt

No successful repair reported for this finding.

0
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 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

If you did that and brought it to my shop, we would charge you extra diagnostics time to compensate for the data lost when you disconnected the battery...................

Original post Read captured discussion
P0456 Check Engine Light -08 C4 Cabriolet

Disconnect battery terminals in case it's a latched fault

Suggestion or failed attempt

No successful repair reported for this finding.

0
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 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

I may try disconnecting the battery terminals in case it's a latched fault.

Original post Read captured discussion
P0456 Check Engine Light -08 C4 Cabriolet

Replace gas cap first; is

Suggestion or failed attempt

No successful repair reported for this finding.

0
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 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

I'm going to try replacing the gas cap first; is that a good start?

Original post Read captured discussion
P0456 Check Engine Light -08 C4 Cabriolet
Frequently discussed actions (5)

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

Check o ring

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

Check the O ring on the cap for cracks.

Original post Read captured discussion
P0456 Check Engine Light -08 C4 Cabriolet

Disconnect battery

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

If you did that and brought it to my shop, we would charge you extra diagnostics time to compensate for the data lost when you disconnected the battery...................

Original post Read captured discussion
P0456 Check Engine Light -08 C4 Cabriolet

Disconnect battery terminals in case it's a latched fault

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

I may try disconnecting the battery terminals in case it's a latched fault.

Original post Read captured discussion
P0456 Check Engine Light -08 C4 Cabriolet

Replace gas cap and the light remained

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 just replaced the gas cap and the light remained on.

Original post Read captured discussion
P0456 Check Engine Light -08 C4 Cabriolet

Replace gas cap first; 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 · Original poster

I'm going to try replacing the gas cap first; is that a good start?

Original post Read captured discussion
P0456 Check Engine Light -08 C4 Cabriolet
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.

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

  • Pelican Parts: 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: 20261026T212127Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources

POST 1 / ORIGINAL POSTEROriginal post

Hello all, I recently purchased my first 911: a 2008 C4 Cabriolet. About two weeks after purchase, my check engine light came on and the error code os P0456. From what I've read so far this seems pretty benign with likely cu'prit being my fuel cap or a vent valve. Does anyone have any experience with this fault? I'm going to try replacing the gas cap first; is that a good start? Regards, Jim

POST 2Original post

Check the O ring on the cap for cracks. Car is now 10 years old. Could be any part of the evap system. If O ring is good you might be better off having a better diagnosis then continuing to swap parts until you find the right one.

POST 3 / ORIGINAL POSTEROriginal post

Thank you Tony. I just replaced the gas cap and the light remained on. I may try disconnecting the battery terminals in case it's a latched fault. If that doesn't work I'll probably take it to a shop and have them isolate it.

POST 4Original post

Quotes source post: 9954217

If you did that and brought it to my shop, we would charge you extra diagnostics time to compensate for the data lost when you disconnected the battery...................

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