Operation CHARM: Car repair manuals for everyone.

Knock Sensor: Description and Operation




The knock sensor is attached to the cylinder block. It senses engine knocking using a piezoelectric element. A knocking vibration from the cylinder block is sensed as vibrational pressure. This pressure is converted into a voltage signal and sent to the ECM.

* Freeze frame data is not stored in the ECM for the knock sensor. The MIL will not light for knock sensor malfunction.