Electronic Actuator Failure & Repair

Actuator failure – signs and symptoms


There are numerous symptoms of a faulty or failed actuator, including:

  • A flashing engine management light

  • Complete loss of power, causing the vehicle to enter limp mode

  • Intermittent low pressure

  • Low boost

  • Overboost

  • Noise from the turbocharger

  • ECU error symptoms control

  • Fault codes


Causes of actuator failure

  • Gearbox failure: ‘Sticky vanes’ caused by sludging or the build-up of carbon could result in REA/SREA failure. In such instances, the variable geometry mechanism pulls a higher current than the motor is designed to take. This can cause the motor to burn out or cause the failure of the plastic worm gears. Symptoms include low boost and the vehicle entering limp mode. When repairing the electronic actuator, it is important that the worm gears and motor have the correct ratio in order to avoid immediate failure. In many instances, the gearbox failure will not damage the unit’s existing black cap or electronics, meaning they could be reused. A Diesel Particulate Filter (DPF) or Catalytic Convertor that becomes blocked, a faulty Electronic gas Recirculation (EGR) valve or incorrect fuel/air mixture can cause carbon (soot) build up in the turbocharger.  This carbon causes restriction in the Variable Nozzle Turbine (VNT) vanes, which makes it increasingly difficult for the actuator to move the vanes. The extra stress can cause damage that can wear out the actuator's components, such as the motor and worm gear/gearbox.

  • Board connectors: The expansion and contraction of wire connectors could eventually lead to breakages and the failure of an electronic actuator. This fault can be difficult to identify as the problem can only be detected once the actuator has heated up.

  • Turbo mishandling: A turbo connector that has been knocked or struck could break. In these instances, a replacement of the entire unit will be needed.

  • Foreign object damage: Damage to a vehicle’s turbo or actuator could be caused by a foreign object within the engine compartment. In such instances, it is important to assess the nature and extent of the damage in order to determine whether a repair or full replacement is required.

  • Water ingress: Electronic actuators may be more susceptible to water ingress owing to the position of the turbo in the engine compartment. When this occurs, the actuator can rust or become contaminated, giving incorrect signals and ultimately breaking.

  • Engine Vibration: A vehicle’s constant vibration can slowly cause wear to the electronic actuator and eventually cause it to fail.

  • Power loss: A turbo will operate inefficiently when an electronic actuator fails to open the nozzle ring assembly vanes under acceleration. Vanes in a closed position can cause the engine to choke or the turbine to overspeed. In contrast, vanes that are open more than necessary will cause the turbo to ‘lag’ and respond too slowly. In such instances, it is important to identify the cause of the electronic actuator failure.


Actuator repairs


REA and SREAs are complex devices that cannot be used interchangeably with different gearboxes or black caps. As the software in each black cap is uniquely programmed to the turbo, the black caps are not serviceable parts and the actuator can easily be taken outside of specification. It is therefore important to have your actuator repaired by someone with the skills and ‘know-how’ to fix your unit using the correct calibration settings to avoid poor performance or complete failure. Depending on the damage, a full replacement unit may be the only solution. With all failures, it is vital to check the turbocharger even if the electronic actuator appears to be the problem.


How we can help


Wear or faults on your electronic actuator can render your entire turbocharger useless. We offer a full diagnosis and repair service where our technicians will test and strip your actuator down to its core components. As standard, we will replace your motor and resolder the board connectors. Common faults, such as dry solder joints, worn or damaged gearbox/worm gears or faulty motors can be easily fixed. 


Contact our technical department for advice on 01302 896 460.