Knock Sensor: Description and Operation

If combustion knock is detected by the Knock Sensor (KS), ignition timing, which is normally at optimum advance, may be retarded on specific cylinders.

Knock sensors use a piezo-electric sensing element to detect broad band (2 kHz to 20 kHz) engine accelerations.

Output of sensor:
Charge sensitivity 37.5 pC/g nominal
Voltage sensitivity 29 + 15 % mV/g