P04C6: Fuel Fill Door Lock Position Sensor Circuit High

What it means

Same as P04C3 with the signal voltage above the plausible range. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.

How it works

The lock-position sensor reports the fuel-fill door lock's position to the control module. P04C6 sets when the sensor signal rises above the expected electrical range, for example if the signal wire is shorted to a supply source.

Common causes

Most likely first.

1. Signal shorted to supply
2. Connector pins corroded - high contact resistance
3. Supply wire pinched against B+ source

Symptoms

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

How to diagnose it

1. Review freeze-frame data and scan-tool position feedback to confirm when the signal reads high relative to lock commands.
2. Inspect the position-sensor connector and harness for moisture, corrosion, pushed-back pins, chafing, or contact with a supply wire.
3. Move the harness gently while monitoring the sensor reading to check for a change in the high signal.
4. Follow the wiring diagram to test the sensor signal for a short to supply, using the manufacturer's procedure.
5. If wiring and connectors pass, test the position sensor and module input against the manufacturer's specification.

Common fixes

• Clean and secure a loose or corroded position-sensor connector.
• Repair a pinched or chafed signal wire that contacts a supply circuit.
• Replace a damaged terminal or connector seal that allows water in.
• Replace the position sensor or repair the module only if testing confirms the fault there.

Can I keep driving?

Driving is generally safe if the fuel-fill door is closed and secure, but its lock status may be reported incorrectly. Confirm the door is latched and arrange repair if the lock will not operate reliably.