DTC P0324: Knock Control System Error: Description
WARNING: This page is about a different car, the 2003 Cadillac CTS. However, it is still accessible from the selected car via links, so may be relevant.
The Knock Sensor (KS) system is used in order to detect any engine detonation, or spark knock. The Engine Control Module (ECM) will retard the spark timing based on the signals from the KS. The KS produces an AC voltage that is sent to the ECM. The amount of AC voltage produced is proportional to the amount of knock.
An operating engine produces a normal amount of engine mechanical vibration, or noise. The knock sensors will produce an AC voltage signal from this noise. When the engine is operating, the ECM will learn the minimum and maximum amplitude of the noise the engine produces. If the ECM will not allow proper diagnosis of the KS system, DTC P0324 will set.