P04B5Fuel Fill Door Stuck Open
- 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
- Plug-in and some full hybrids keep the fuel tank sealed while driving, separated from the charcoal canister by a valve. When the driver presses the fuel button, the system opens the valve, lets the pressure escape into the canister and only then unlocks the filler door. A switch reports whether the door is open or closed, so that the tank can be sealed again afterwards. P04B5 means the door is not detected as closed and latched although the system expects it to be. Ford (C-Max and Fusion Energi 2013–17, MKZ hybrid) names a door not fully latched or opened by an accidental button press, with a message and the code in the third drive cycle; on the MKZ a door pressed during unlocking can confuse the latch – reset by pressing the button and waiting 12 s. Stellantis re-enables the check only after more than 16 miles and names a missing plunger or magnet, the cap tether blocking it, or a short to ground of the status line.
- What you may notice
- Check engine light on (depending on the maker)
- Fuel door open message in the instrument cluster
- Door stays open or does not latch
- Likely causes
- LikelyDoor not fully latched after refuelling or opened by an accidental button press
- PossibleFuel cap tether blocking the plunger or latch
- PossiblePlunger missing or loose, magnet or latch motor shifted or faulty
- RareStatus line of the door switch shorted to ground
- 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: €0 – €250
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.