Fuel filler door lock actuator worn, sticking or jammed mechanically; Position sensor or switch inside the lock assembly faulty or giving an erratic signal; Damaged, corroded or loose wiring or connector at the filler door lock; Dirt, ice, corrosion or a bent filler door or latch preventing full travel; Low or unstable supply voltage or a poor earth to the lock circuit; Fault in the controlling module (body or fuel system control unit).

P04C4

Fuel Fill Door Lock Position Sensor/Switch Circuit Range/Performance.

Generic
Powertrain
Generic code
Low severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
4: AreaAuxiliary emission controls
C4: FaultThe specific fault in that area

What it means

P04C4 means the control unit has seen a signal from the fuel filler door lock position sensor or switch that does not match what it expects. The reported position may disagree with the commanded lock or unlock state, may be implausible, or may be slow to change. The fault is a range or performance problem, not a plain open or short circuit. The exact layout of the lock, its sensor and the controlling module varies by model.

Symptoms

Warning light on, or a message about the fuel filler door or fuel system
Fuel filler door will not open, or will not stay locked
Fuel filler door does not respond to the release button or remote unlock
Lock motor can be heard buzzing or clicking but the door does not move properly
Difficulty refuelling on vehicles with a pressurised or sealed fuel system

Possible causes

Fuel filler door lock actuator worn, sticking or jammed mechanicallylikely
Position sensor or switch inside the lock assembly faulty or giving an erratic signallikely
Damaged, corroded or loose wiring or connector at the filler door locklikely
Dirt, ice, corrosion or a bent filler door or latch preventing full travelpossible
Low or unstable supply voltage or a poor earth to the lock circuitpossible
Fault in the controlling module (body or fuel system control unit)rare

How to diagnose

Read all stored codes and freeze frame data, and note any related body, central locking, fuel system or EVAP codes
Operate the filler door release and lock several times and observe whether the door and lock move fully and smoothly
Inspect the filler door, hinge, latch and lock area for dirt, corrosion, ice, damage or obstruction
Inspect the wiring and connector at the lock for water ingress, corrosion, chafing and pin tension
Check the battery condition and charging voltage, since low voltage can cause erratic lock operation
Using live data, compare the commanded lock state with the reported position sensor state while operating the lock
Check the supply, earth and signal circuits at the lock against the manufacturer's wiring diagram, following the model-specific procedure
Test the lock actuator and position sensor against the manufacturer's specification, and only then consider the controlling module

How to fix

Clean and free off a sticking lock, latch or filler door, and correct any bent or misaligned parts
Repair or replace damaged wiring, and clean or replace corroded connectors
Replace the fuel filler door lock actuator or its position sensor if testing shows it is faulty
Restore a good power supply and earth, and correct any battery or charging fault
Repair or replace the controlling module only if all other causes are ruled out, then clear the code and confirm it does not return

Can I keep driving?

Low severity

The car can normally be driven as usual, but book it in soon in case the door sticks locked and you cannot refuel. If the fuel system warning is also showing, have it checked promptly.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.