P04CB: Fuel Fill Door Open Request Sensor/Switch Circuit High
What to do
Find the manual fuel door release in the boot — usually a small cable or lever behind a trim panel. It still works with this fault, so you can refuel normally while the repair is arranged.
Say where the release button is on your car and exactly what happens when you press it. Nothing at all, an occasional response, or a click without the door opening all point at different things and genuinely narrow the diagnosis.
Mention any recent interior work, or anything heavy carried in the boot or footwells, since the wiring for this switch runs under trim and is easily disturbed.
Say if it worked intermittently before stopping. That points at a wire broken inside its insulation where it flexes with the door, which is the commonest cause.
What this code means
The circuit for the fuel filler door release request is reading above its valid range.
This is the request, not the door — the switch, button or touch sensor a driver uses to ask for the door to open. A fault here means the vehicle cannot hear the request, which presents as a release that does nothing while the door mechanism is entirely healthy.
Reading high on a switch circuit means an open connection or a short to a supply voltage, and on this particular circuit the open case dominates. The request switch is usually in the cabin — on the dash, in a door pocket, or on the driver's door card — and its wiring runs through a door loom or under trim that gets disturbed by ordinary use and by any interior work.
The door loom is the classic location. Wires that flex every time a door opens eventually fatigue and break inside intact insulation, which is invisible and produces exactly this. It is also why the fault often appears intermittently before it becomes permanent.
Where the release is a touch-sensitive pad on the door itself rather than a switch inside, water ingress is the usual cause, and the sensor is normally part of the door assembly.
The manual release in the boot still works, so this is an inconvenience rather than a stranding — but it is worth locating that release before it is needed.
Likely causes
Start here
- Open circuit in switch wiring · moderate
- Corroded or loose connector · easy
- Broken wire in the door loom · moderate
Less common
Symptoms
Components involved
Information, not instruction
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Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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