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Knock Sensor: Description and Operation

Knock Sensor:

PURPOSE
The knock sensor is a piezoelectric element tuned to resonate at the same frequency as engine knock (detonation).

LOCATION
Mounted in the engine block.

OPERATION
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 to the ECU through the KNK pin.