Abstract: A controller for preventing unnecessary idling of a vehicle engine, such as when the vehicle is left unattended with the engine idling. The controller includes a motion detector having a predetermined detection pattern directed to the driver's position within the vehicle. The motion detector is preferably a passive infrared motion detector. When the motion detector fails to detect the presence of the driver for a preselected time, the engine is shut down by a control circuit. The engine idle shut-down controller may also include various sensors, such as a vehicle speed sensor, and engine load and temperature sensors, to determine that the vehicle is not moving before shutting down the engine.