P04C3: Fuel Fill Door Lock Position Sensor Circuit

What it means

A general circuit fault is detected on the fuel fill door lock position sensor or switch. Without it the ECU cannot determine whether the lock has actually engaged or released.

How it works

A position sensor or switch reports whether the fuel-fill door lock is engaged or released. P04C3 sets when the module detects a general electrical fault in that sensor circuit, so it may not be able to confirm the lock's actual position.

Common causes

Most likely first.

1. Open or short in sensor wiring
2. Loose or corroded connector
3. Failed lock-position sensor or switch

Symptoms

• Lock status may be unavailable or incorrect
• Fuel-fill door may not lock or unlock as expected

How to diagnose it

1. Check freeze-frame data and scan-tool lock command and position status to see whether feedback is missing or implausible.
2. Inspect the lock-position sensor or switch connector for looseness, corrosion, moisture, or damaged pins.
3. Trace the sensor wiring for an open, short, or physical damage near the lock mechanism and harness bends.
4. Test the sensor circuit and sensor operation using the wiring diagram and the manufacturer's specification.
5. If the sensor and wiring pass, check the module connector and input circuit for a fault.

Common fixes

• Reconnect or clean a loose or corroded sensor connector.
• Repair damaged sensor wiring or replace a faulty terminal.
• Replace a failed lock-position sensor or switch.
• Repair the module input circuit only if testing confirms an internal module fault.

Can I keep driving?

You can generally drive if the fuel-fill door is shut, but the vehicle may not reliably report whether its lock is engaged. Check that the door is secure before driving and have the fault addressed if it will not latch.