Describes the operation of the APP or accelerator position sensor. The APP sensor is found in almost every vehicle today. This is a component of the Drive-By-Wire system, which does away with the throttle cable. In a DBW system, the ECM receives an input from the APP sensor and then commands the appropriate throttle opening using a throttle actuator motor. See how this device works with this video. Then, go further and view our other video on how to test the APP sensor.