Knock Sensor (KS)

The knock sensor is a piezoelectric device which detects abnormal engine vibrations (spark knock) in the engine. This vibration results in the production of a very low AC signal, which is sent from the knock sensor to the KS module (integral to PCM/VCM). The PCM/VCM then retards ignition timing until the engine knock ceases. Two knock sensors are used on some models.

A fault in the KS circuit may set a Diagnostic Trouble Code (DTC). See the TESTS W/CODES article. When a related DTC is not present and the KS system is the suspected cause of a driveability problem, perform functional check of KS system. See the SYSTEM/COMPONENT TESTS article.