Knock Sensor: Description and Operation

Knock Sensor:

PURPOSE
Knock Sensor (KS) detects engine knock and sends a signal to the Powertrain Control Module (PCM). When knocking occurs, PCM retards ignition timing until knock ceases.

OPERATION
When sensor crystal structure is distorted by a knock of sufficient intensity and frequency, a small voltage potential is created. Voltage signal is interpreted by PCM as engine knock and timing is retarded as needed until knock is eliminated.

CONSTRUCTION
Knock sensor contains a crystal element with electrodes attached to opposing sides.