Knock Sensor: Description and Operation

Knock Sensor:

PURPOSE
The knock sensor senses engine detonation and reports to the ECM. The sensor input is used to determine proper ignition and injection timing.

LOCATION
The sensor is mounted to the side of the engine block.

CONSTRUCTION
The sensor consists of a piezoelectric element tuned to resonate at the same frequency as engine knock (detonation).

OPERATION
When the engine knocks (detonates), the piezo element resonates at the same frequency and produces a voltage that varies according to the amplitude of the knock. This voltage is the input signal to the ECM. This signal is input to the ECM through the KNK pin.