Knock Sensor System Operation

Knock Sensor Cutaway:

Knock Sensor System Operation

The knock sensor system is used to detect engine detonation. The knock sensor(s) produce an AC voltage which is sent to the PCM. The PCM will retard the spark timing based on signals from the KS sensors. The amount of AC voltage produced by the sensors is determined by the amount of knock. The PCM then adjusts the Ignition Control (IC) to reduce the spark knock.

The scan tool has several positions for diagnosing the KS circuit.
^ Knock Retard indicates the amount of spark the PCM is removing from the IC spark advance in response to the signal from the knock sensors.
^ Spark indicates the amount of spark advance being commanded by the PCM on the IC circuit.

DTC P0325 indicates an internal PCM malfunction related to the KS system. DTCs P0327 and P0332 indicates that a Knock sensor or Knock sensor circuit is malfunctioning. If these DTCs are set, Refer to applicable DTC table.