Forester S F4-2.5L DOHC (1998)
Knock Sensor: Description and Operation
PURPOSE/OPERATION
The knock sensor records engine vibrations (detonation), and signals the Engine Control Module, so that correct timing configurations can be set.
The sensor generates a signal whenever a vibration is sensed. When a knock occurs, the piezo-electric crystal (piezo element) in the sensor is
compressed by the weight above it. The squeezing of the crystal, generates a low voltage signal readable by the Engine Control Module.
