Circuit Description
WARNING: This page is about a different car, the 2007 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
This diagnostic monitors the activity on the knock sensor (KS) circuit. The KS is used to detect engine detonation. The KS is constructed of a piezoelectric element which generates an AC signal when vibrated. Normal engine operation will cause the KS to generate a signal of a certain known frequency. When engine knock is present, the KS frequency changes which signals the powertrain control module (PCM) to retard ignition timing. By retarding the ignition timing, the engine detonation detected should be reduced. If the PCM detects the KS signal is not within a predetermined range, this DTC sets.