An actuator is a component in a car that converts energy into a physical action or force. It is an essential part of electronic control systems in passenger cars and commercial vehicles. Actuators perform a variety of performance and convenience functions, such as controlling the throttle, directing airflow in the climate control system, and operating power seats and liftgates. Most actuators are electric motors or electromagnetic valves that adjust flaps, regulate the flow of fluids, or actuate pumps to build up pressure. They take their orders from microprocessors that manage the various electronic systems in vehicles. Actuators are also used to lock and unlock car doors, for remote control of fuel filler flaps, boot lids, engine bonnets, and storage compartments.

When you step on the gas pedal, there is no mechanical connection that allows more air and fuel into the engine. Instead, a sensor tells the electronic control unit (ECU) how far down you’ve pushed the pedal, and an actuator opens the throttle accordingly. Actuators are powered by electricity, and some are mechanical and activated by airflow or fluid pressure. They are out of sight and out of mind until one fails, and the only time you’re likely to hear about them is when a technician says an actuator needs to be replaced because a sunroof won’t close, the air conditioner doesn’t blow cold air, or there’s another malfunction.