Operation CHARM: Car repair manuals for everyone.

Knock Sensor: Description and Operation

Underhood Component Location:





The Knock Sensor is mounted on the side of the cylinder block (# 22 in image). All 4 cylinders are monitored by the knock sensor.

The signal from the knock sensor is used by the Motronic control module for adaptive cylinder selective knock control. The ignition timing of an individual cylinder can be retarded if a knock is detected. If knock continues, the ECM will switch from the premium fuel ignition map to the ignition map for regular fuel.

Knock control is now adaptive which means that the system will adapt to fuel quality and driving conditions.