Knock Sensor
WARNING: This page does not describe the selected car, but rather 33 other vehicles, including the 2002 Saturn Vue, 2002 Pontiac Montana, 2002 Pontiac Aztek, 2002 Oldsmobile Silhouette, and 2002 Oldsmobile Bravada. However, it is still accessible from the selected car via links, so may be relevant.
The Knock Sensor (KS) 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 KS to the KS module (integral to PCM). The PCM then retards ignition timing until the engine knock ceases. Two KS are used on some models.
A fault in the KS circuit may set a DTC. See appropriate SELF-DIAGNOSTICS 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 appropriate SYSTEM & COMPONENT TESTING article.