P04C1Fuel Fill Door Unlock Control Circuit Low
- 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). P04C1 concerns the unlock circuit: the voltage in the control circuit is below the expected range – typically the control line is shorted to ground. Mitsubishi's Outlander PHEV from 2023 uses an internal driver check in refuelling mode. Mitsubishi shows a 'refuelling system service required' message for these codes and gives no drive-cycle pattern.
- What you may notice
- Filler door does not open or lock as commanded
- Refuelling system message in the instrument cluster
- Possibly check engine light
- Likely causes
- LikelyControl line chafed against the body (short to ground)
- PossibleWater or corrosion at the connector
- PossibleActuator shorted internally
- RareRelay or module driver faulty
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €60 – €350
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.