P04CD: Fuel Fill Door Open Request Sensor or Switch Stuck On

What it means

The open-request switch is stuck in the active state - the ECU continuously reads a request to open the fuel fill door. Either the switch is mechanically held closed or the line is shorted to its active level.

How it works

The fuel-fill door open-request switch should be inactive until the driver presses it. P04CD sets when the control module continually sees an active request, which can result from a switch stuck closed or an input held at its active electrical level.

Common causes

Most likely first.

1. Switch contact mechanically stuck closed
2. Carbon or debris buildup preventing free movement
3. Component wear with age - mechanical play

Symptoms

• Fuel-fill door may release without a deliberate request
• Open-request button may appear continuously active

How to diagnose it

1. Check scan-tool live data with the button untouched to confirm whether the request remains active.
2. Inspect the button for sticking, debris, restricted movement, or damage that could hold its contact closed.
3. Disconnect the switch as directed by the circuit diagram and see whether the input returns to inactive, helping distinguish a switch fault from a harness fault.
4. Inspect the wiring for a short to the circuit's active level and check connector terminals for damage or corrosion.
5. Test switch operation and the module input against the manufacturer's specification if the fault remains.

Common fixes

• Remove debris or free a mechanically stuck button if it is serviceable.
• Repair a signal wire shorted to the active level.
• Reconnect or repair damaged switch connector terminals.
• Replace the switch if it remains electrically active when released.

Can I keep driving?

If the door is secure, driving is generally possible, but check that it will stay closed and that you can access the filler when needed. A continuously active request can cause unwanted release or drain the door mechanism if it keeps operating.