P04C6

What it means

P04C6 means the control unit has seen the signal from the fuel filler door lock position sensor or switch sitting higher than its expected range. This usually points to an open circuit, a short to voltage, or a fault in the sensor or switch built into the lock mechanism. The exact layout and which module monitors it depend on the vehicle.

Symptoms

• Warning lamp on, or a fuel door or lock warning message
• Fuel filler door will not open or will not release
• Fuel filler door will not lock or latch properly
• Fuel door release works intermittently
• Possible difficulty refuelling on models that depressurise the tank before the door opens

Possible causes

• Faulty position sensor or switch inside the fuel door lock actuatorlikely
• Corroded, loose or damaged connector at the actuatorlikely
• Open circuit or high resistance in the signal or ground wire, giving a high signal voltagepossible
• Signal wire shorted to a voltage supplypossible
• Mechanical jam or damage to the lock or filler door, so the sensor reads an incorrect positionpossible
• Fault in the controlling module or its softwarerare

How to diagnose

1. Read all stored and pending codes and note the freeze frame data for when the fault set
2. Check for related codes covering the fuel door lock actuator, body control or evaporative system, and deal with those first if present
3. Inspect the filler door, hinge and lock for damage, debris, ice or a mechanical jam, and test the operation by hand and with the release control
4. Inspect the wiring and connector at the actuator and along its route for chafing, water ingress, corrosion and pushed-out pins
5. Watch the lock position signal in live data while operating the release, and see whether it changes or stays stuck high
6. Check the supply, signal and ground circuits at the connector against the manufacturer's wiring diagram and specified values
7. Test the wiring for open circuits and shorts to voltage, with the connector unplugged and the battery safely isolated as the procedure requires
8. Check the sensor or switch against the manufacturer's specification, and only then suspect the control module

How to fix

• Repair or replace damaged or corroded wiring and connectors in the circuit
• Replace the fuel door lock actuator or its position sensor or switch if it is faulty
• Free, repair or replace a jammed or damaged filler door or lock mechanism
• Repair any short to voltage or open circuit found in the signal or ground wire
• Update or repair the control module software or replace the module only if a fault is confirmed and the manufacturer lists it as a known cause
• Clear the code after repair and confirm the fault does not return when the lock is operated

Can I keep driving?

Nearby codes

• P04C5GenericFuel Fill Door Lock Position Sensor/Switch Circuit Low
• P04C7GenericFuel Fill Door Lock Position Sensor/Switch Circuit Intermittent/Erratic