P04CAFuel Fill Door Open Request Sensor/Switch 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). P04CA means the button line is below its valid range. Ford's Escape and Corsair 2.5 (2020–26) set it with an open supply circuit to the button, so the door does not open. With buttons that pull to ground (Mitsubishi), a permanently low line appears as stuck on (P04CD) instead.
- 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
- LikelyButton supply circuit open (Ford: supply circuit or splice)
- LikelyButton line shorted to ground
- PossibleFuel button faulty
- RareModule
- 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.