P04C9Fuel Fill Door Open Request Sensor/Switch Performance/Stuck Off
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- On plug-in hybrids with a sealed, pressurised tank, pressing the fuel button (open request) starts a refuelling mode: the module opens the tank valve, releases the pressure into the charcoal canister and only then unlocks the filler door via an electric actuator (Ford patent). P04C9 means the button gives no or no plausible signal when it should be pressed, or the door is found open without a button press – as after use of the emergency release. No manufacturer document available to us uses this code; the description follows CARB's rules for input and output components and patents on the door actuator.
- What you may notice
- Fuel button has no effect, door does not open
- Refuelling system message in the instrument cluster
- Refuelling only via emergency release
- Likely causes
- LikelyFuel button faulty
- LikelyWire between button and module open
- PossibleDoor opened via the emergency release
- PossibleButton ground open
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Easy · Often possible to do yourself.Typical cost: €20 – €200
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.