Broken or chafed wires in the harness that runs from the body to the fuel fill door, often due to flexing or corrosion.; Failed fuel fill door lock actuator, where the internal motor or solenoid has an open winding.; Corroded or disconnected electrical connector at the lock actuator or at the body control module (BCM).; Blown fuse that supplies power to the fuel door lock circuit, though this usually affects other functions too.; Faulty body control module (BCM) or PCM driver circuit, though this is less common.; Damage to the fuel door lock mechanism from impact or debris, causing the actuator to bind and draw abnormal current.

DTC codes / P04xx · Auxiliary emission controls / P04BB

P04BBFuel Fill Door Lock Control Circuit/Open

Q: What does code P04BB mean?

Fuel Fill Door Lock Control Circuit/Open. P04BB indicates that the powertrain control module (PCM) has detected an open circuit in the fuel fill door lock control circuit, meaning the electrical path to the lock actuator is broken. The PCM commands the lock but sees no continuity or unexpected voltage, so it sets this generic body-integrated code.

P04BB indicates that the powertrain control module (PCM) has detected an open circuit in the fuel fill door lock control circuit, meaning the electrical path to the lock actuator is broken. The PCM commands the lock but sees no continuity or unexpected voltage, so it sets this generic body-integrated code.

SystemPowertrain

Code typeGeneric (all makes)

SeverityLow

Fix difficultyIntermediate

AreaAuxiliary emission controls

Symptoms you may notice

The fuel fill door lock does not lock or unlock when commanded, remaining stuck in one position.
A warning light on the dashboard, often the check engine light or a dedicated message, appears.
The fuel door may be difficult to open manually if the lock is stuck engaged.
A clicking or buzzing sound may be heard from the door area when the lock is activated, indicating the actuator is trying to move.
Often no symptoms besides the warning light, as the lock may still function intermittently or the driver may not notice the failure.
Remote key fob or central locking may not affect the fuel door, while other doors work normally.

Common causes, most likely first

Broken or chafed wires in the harness that runs from the body to the fuel fill door, often due to flexing or corrosion.
Failed fuel fill door lock actuator, where the internal motor or solenoid has an open winding.
Corroded or disconnected electrical connector at the lock actuator or at the body control module (BCM).
Blown fuse that supplies power to the fuel door lock circuit, though this usually affects other functions too.
Faulty body control module (BCM) or PCM driver circuit, though this is less common.
Damage to the fuel door lock mechanism from impact or debris, causing the actuator to bind and draw abnormal current.

How to diagnose and fix it

Verify the code with a scan tool and check for any related body codes in the BCM or PCM.
Inspect the fuel fill door lock actuator connector for corrosion, tightness, and clean terminals; apply dielectric grease if needed.
Check the wiring harness between the body and the fuel door for continuity and signs of chafing, especially at flex points.
Test the actuator directly by applying 12 volts and ground to its terminals to confirm it operates; replace if it does not.
Check the fuse that powers the fuel door lock circuit and replace if blown, then recheck for shorts.
If the actuator and wiring are good, test the control module output with a multimeter or oscilloscope to confirm the driver circuit is functioning.
Clear the code and verify the repair by cycling the lock several times and confirming the code does not return.

Common oversights in fuel door lock diagnosis

A broken wire inside the rubber boot between the body and the fuel door is a frequent cause that visual inspection alone may miss; always flex the harness while testing continuity.
The fuel fill door lock often shares a circuit with the central locking system, so a fault elsewhere can set this code even if the fuel door lock appears to work.
After replacing the actuator, some vehicles require a relearn or calibration procedure for the body control module to recognize the new part.
A sticking lock mechanism can cause the actuator to overheat and fail, so always check for mechanical binding before installing a new actuator.
This code can be set by a low battery or voltage spike, so clear it and retest before condemning any component.

Can I keep driving with P04BB?

The vehicle remains safe to drive because the fuel fill door lock is a convenience feature and does not affect engine operation or safety systems. Avoid forcing the fuel door open if it is stuck, as this can damage the actuator or door, and have the circuit inspected at your next service.

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.