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DTC codes / P04xx · Auxiliary emission controls / P04BE

P04BEFuel Fill Door Lock Control Circuit High

P04BE indicates that the powertrain control module (PCM) has detected an abnormally high voltage on the fuel fill door lock control circuit, which typically points to an open circuit, a short to voltage, or a failed lock actuator. The PCM commands the lock actuator based on vehicle speed and door status, and it monitors the circuit for expected voltage changes; a high reading means the circuit is not completing the path to ground as designed.

SystemPowertrain
Code typeGeneric (all makes)
SeverityLow
Fix difficultyIntermediate
AreaAuxiliary emission controls

Symptoms you may notice

  • The fuel fill door may not lock or unlock when commanded, leaving it stuck in one position.
  • A warning light on the dashboard, often the check engine light or a dedicated message, appears.
  • The fuel fill door may appear closed but not be securely latched, allowing it to open while driving.
  • Remote or central locking functions may not affect the fuel door, even though other doors work normally.
  • Often no symptoms besides the warning light, especially if the actuator fails in the unlocked position.

Common causes, most likely first

  1. Open circuit in the fuel fill door lock control wiring, such as a broken wire or disconnected connector.
  2. Corroded or damaged electrical connector at the fuel fill door lock actuator.
  3. Failed fuel fill door lock actuator solenoid or motor.
  4. Short to voltage on the control circuit, often from chafed wiring against a metal body panel.
  5. Faulty powertrain control module (PCM) or body control module (BCM) driver for the lock circuit, though this is less common.
  6. Poor ground connection for the fuel fill door lock actuator, causing the circuit to read high voltage.

How to diagnose and fix it

  1. Use a scan tool to command the fuel fill door lock actuator on and off while listening for actuator operation and watching live data for the circuit voltage.
  2. Visually inspect the wiring and connector at the fuel fill door lock actuator for damage, corrosion, or loose pins.
  3. Disconnect the actuator and measure resistance across its terminals; compare to specifications to rule out a failed actuator.
  4. Check for battery voltage on the control wire at the actuator connector with the key on and the lock command active; if voltage is present when it should be grounded, suspect a short to voltage.
  5. Perform a voltage drop test on the ground circuit for the actuator to confirm a good ground path.
  6. If wiring and actuator test good, check the PCM/BCM connector and driver circuit for faults, and verify software updates if applicable.
  7. Repair or replace the faulty wiring, connector, or actuator as needed, then clear the code and verify the repair with a test drive and actuator command.

What the high voltage reading really means

  • A high voltage code on an actuator circuit often means the circuit is open, not that the actuator has failed; the PCM sees voltage because no current flows to pull the signal low.
  • The fuel fill door lock is frequently tied to the central locking system, so a fault in the door lock wiring or a failing body control module can set this code even when the fuel door actuator itself is fine.
  • Water intrusion into the fuel fill door area or the connector can cause corrosion that raises resistance and triggers a high voltage code, especially on vehicles driven in wet or salty conditions.
  • Technicians sometimes replace the actuator only to find the code returns because the real problem is a chafed wire in the harness near the hinge or a poor ground behind a trim panel.
  • This code does not always mean the fuel door will not lock; if the actuator fails in the unlocked position, the driver may never notice a problem beyond the warning light.

Can I keep driving with P04BE?

The vehicle remains safe to drive because the fuel fill door lock is a convenience and security feature, not a safety system. Avoid forcing the fuel door open or closed, and have the circuit inspected soon to prevent the door from becoming stuck or failing to secure the fuel cap area.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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