Knock Sensor: Description and Operation

Purpose:
The knock sensor (KS) is mounted in the engine block near the cylinders and is used to detect abnormal vibration (spark knocking) within the engine block.

Operation:
The sensor produces an AC output voltage which increases with the severity of the engine knock. The PCM will reduce spark timing, to reduce engine knock.

This retard of spark timing allows the engine to use maximum spark advance to improve driveability and fuel economy.

The knock sensor signal is only used during the TDC combustion event, which is determined by the 6X signal (knock windowing).