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 (only on vehicles using PCM). On vehicles equipped with VCM, KS module is integral to 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 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 SYSTEM/COMPONENT TESTS article.