4 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHUpdate: 04 C4S won't take gas
Reported or suspected cause
fuel line vent valve
Suggestion or failed attempt
No successful repair reported for this finding.
0
Identified cause
1
Suspected cause
0
Reported fixes
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Discussions that suspect a cause
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Suspected cause · Original poster
I don't think the problem is with the fuel line vent valve.
Leading evidence: 'fuel line vent valve' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, the most frequently mentioned possible cause is 'fuel line vent valve' (1 discussions; 0 report identifying it and 1 suggest it). The most frequently discussed action is 'Check with your trusted porsche tech' (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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Suggestion
You'll have to check with your trusted Porsche tech.
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Suggestion
The dealer tech should be able to query for this using the Porsche diagnostics computer.
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.
Rennlist: 1 discussions
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Generation: 20261026T113718Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
I don't think the problem is with the fuel line vent valve. I can push a thin tube in the filler tube at least 18". If the vent valve was stuck in the closed position, I don't think the tube would go in. I can't remember when I bought gas last. The tank might be full and that's why it won't take any more gas but the Gauge is reading in the reserve. Does anyone know how to manually check how much fuel is in the tank?
What does the computer say for miles to empty? It's not manual but should give you an idea. Mine get's weird about gas from some stations - have you tried a different pump?
Maybe using the diesel pump? Lol, I know it can't be this, but my wife called me panicking one time saying the gas pump wouldn't fit. She was trying to use diesel.
Maybe the tech has a way involving a makeshift "dipstick" to measure the amount of fuel in the tank, kind of like the tanker delivery truck drivers due when making deliveries at the stations? You'll have to check with your trusted Porsche tech.
The above may be doable through the filler neck but it may require the fuel pump be removed to gain access to the fuel tank.
This may be a problem if you have overfilled the tank as fuel may run out of the tank as the fuel pump cover is removed and the fuel tank's interior is exposed.
To calibrate the fuel level hardware involves emptying the tank and then adding a known quantity of fuel to the tank.
There is an extended OBD2 PID (Parameter ID) (Mode 1, 0x2F) that supplies the fuel level based on the sensor reading. The dealer tech should be able to query for this using the Porsche diagnostics computer. About the only OBD2 code reader/data viewer that might be able to query for this PID is the Durametric.
While knowing the amount of fuel in the tank is important I suspect there's a problem with the fuel system (to state the obvious) that needs addressing. Your test used to eliminate a flap is not conclusive and there can be other things that explain the behavior. Most involve problems with fuel system's venting hardware that is often beyond the DIY auto mechanic's abilities.
This is a source reference. Confirm exact model applicability in the original material.
