Knock Sensor (KS)

Knock is a phenomenon characterized by undesirable vibration and noise, and it may cause engine damage. The Knock Sensor (KS) is installed on the cylinder block and detects engine knock. When knock occurs, vibration from the cylinder block is applied as pressure to a piezoelectric element. When knock occurs, the sensor outputs a voltage signal. The ECM retards ignition timing when knock occurs. If knock disappears after retarding the ignition timing, the ECM advances the ignition timing again. This sequential control can improve engine output, torque and fuel economy.