Knock Sensor: Description and Operation

Function And Operation Principle

Knocking is a phenomenon characterized by undesirable engine detonation or pinging that can cause engine damage. Knock Sensor (KS) senses engine and cylinder block knocking. When knocking occurs, the vibration from the cylinder block is applied as pressure to the piezoelectric element. The sensor transfers the voltage signal higher than the specified value to the PCM and the PCM retards the ignition timing. If the knocking disappears after retarding the ignition timing, the PCM will advance the ignition timing. This sequential control can improve engine power, torque and fuel economy.