Knock Sensor

The knock sensors (KS) detect abnormal vibration (spark knocking) in the engine. The sensors are mounted in the engine block near the cylinders. The KS produce an AC voltage signal under all engine operating conditions. The PCM adjusts the Ignition Control (IC) spark timing based on the amplitude and frequency of the KS signal being received.

The PCM contains integrated KS diagnostic circuitry. The PCM uses the circuitry to diagnose the KS sensors and related wiring. The PCM calculates an average voltage of each knock sensor's signal and performs instantaneous signal voltage readings. The PCM uses the instantaneous signal voltage readings to determine the state of the KS circuitry. If the KS system is operating normally, the PCM should monitor instantaneous KS signal voltage readings varying outside a voltage range above and below the calculated average voltage. If the PCM malfunctions in a manner which does not allow proper diagnosis of the KS circuits, DTC P0325 is set. DTCs P0327 and P0332 are designed to diagnose the knock sensors and related wiring. Problems encountered with the KS system should set a DTC.

Refer to knock Sensor System Description for a complete description of the KS system.