2008 Mercedes-Benz ML320 Fuel Door Release Actuator Replacement Cost

The fuel door release actuator is a mechanism that holds the fuel door shut on a car, truck, or SUV. The actuator may be manually operated by a cable and release lever, or it may be electric.

On some vehicles, the fuel door latches automatically when closed and opens with either a manual (cable-operated) release or an electric solenoid and switch. Some fuel doors are not locked when the vehicle is in park, but lock when vehicle is moving and the door locks actuate. And some vehicles have fuel doors that are not normally locked at all, but which lock for safety if the vehicle is involved in a rear end crash. Vehicles that have a fuel door that is normally locked will also have a release lever or button inside the passenger compartment. In the case of a manual release lever, a cable extends from the lever, along the door sill, and through the quarter panel of the vehicle to the actuator behind the fuel door. An electric release involves a switch in the passenger compartment that controls a solenoid actuator. This type of actuator may or may not be controlled and monitored by the Body Control Module (computer).

Symptoms of a bad fuel door release actuator include, of course, a fuel door that will not open at all. A fuel door that works intermittently, or one that is sluggish to respond, may also be a sign of a failing actuator. With a manual actuator, the release lever may become difficult to pull, or the actuator pin that contacts the fuel door may stick in the open position. An electric actuator may make a clicking sound but refuse to open - or it may stick in the open position. Some drivers will note that the fuel door is not locking with the rest of the doors on the vehicle as it should.

If a fuel door release actuator fails completely, it may be difficult to open the fuel door and add fuel to the vehicle. This is particularly problematic when the door refuses to open at a gas station with an empty fuel tank. The actuator should be inspected and replaced as soon as symptoms appear.

A fuel door release actuator should last the lifetime of the vehicle. Excessive force applied to the release lever of a manual actuator can cause the cable to stretch or break prematurely, or strain and break the attachment points. A dirty actuator pin on an electric model can get gummed up and stick if not kept clean. This places undue stress on the solenoid and can lead to early failure.

A problem with a manual fuel door release actuator that will not open or close properly can usually be detected in the feel of the release lever. If the lever is significantly lose, the cause could be a broken cable. If the lever does not move, or moves with too much effort, the cable or release pin could be dirty or corroded. A technician will actuate the lever and sense if the cable or actuator is faulty. If the vehicle has an electric actuator, the technician will determine if the problem is with the switch or the actuator by testing for power (voltage) at the switch and at the actuator. In the case of an actuator that operates with the central locking system, a scan of the Body Control Module may be necessary.

The general replacement procedure for most fuel door release actuators is similar, however, access to the actuator (and attachment methods) can differ quite a bit. On some vehicles, the boot around the fuel filler neck (where the fuel is added) is removed and the actuator is installed through the fuel access. On other vehicles, it is necessary to remove trim components inside the trunk or in the wheelhouse for access. Electric actuators have a wire plug that needs to be disconnected. Manual actuators sometimes require that the entire cable system be replaced together as a unit with the actuator.

Because it can be difficult to open the fuel door to add fuel should the actuator fail, RepairPal recommends having the problem diagnosed and repaired as soon as symptoms begin. Most vehicles that have locking fuel doors also have some form of manual release in the trunk, but the release can be inconvenient to access, especially at a gas station.

Care should be exercised any time work is being performed around the fuel system. Although the fuel filler neck is designed to keep vapors from moving freely, accidents can still happen.

Replacement of a fuel door release actuator can be done by someone with intermediate DIY experience. With vehicles where an electric actuator is tied into the central locking system, a diagnostic scan and computer reset may be required.