Knock Sensor: Description and Operation

Knock Sensor:

PURPOSE AND LOCATION
Provides an siganl to the ECM during engine detonation. Located on the engine block, below the intake manifold.

OPERATION
Spark knock (detonation) is controlled by an electronic spark control (ESC) system that can retard ignition timing up to 8°. This allows the engine to use maximum spark advance to improve driveability and fuel economy.

The system consists of an ESC module (part of the ECM) and knock sensor. When the sensor detects knock, it produces a voltage signal that is sent to the ESC module (ECM).

The sensor produces an A/C voltage which increases with knock severity. When the voltage increases, the ECM retards ignition timing, therby reducing engine knock.