Knock Sensor: Description and Operation

Knock Sensor:

The Knock Sensor, located on the left side of the front rotor housing above the spark plugs, is a piezoelectric device that generates a small voltage when vibrated at the frequency caused by engine knocking. When the ECU receives a knock signal from the sensor, it retards ignition timing up to 5°. As knocking subsides, timing is advanced until a knock signal is again input from the sensor.