Knock Sensor: Description and Operation

Knock Sensor:

The Knock sensor, mounted in the engine block, is a piezoelectric element tuned to resonate at the same frequency as engine knock (detonation). As 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 ECU. This signal is input through the KNK pin.