Which action best describes the actuator role in engine control?

• A. Sensor
• B. Fuel Injector
• C. Controller
• D. Transmission

Answer: (B)

Actuators are the components that turn electrical control signals into real, physical actions on the engine. The fuel injector fits this role because it takes commands from the engine control unit and translates them into a concrete action—injecting a precise amount of fuel into the intake port or cylinder. Sensors, by contrast, only measure and feed data to the control unit; the controller itself processes data and issues commands but doesn’t perform the physical action. The transmission is part of another system and not part of engine control actuation. So the action that best describes the actuator role is delivering fuel via the injector.