Elantra GLS Sedan L4-2.0L (1999)
Knock Sensor: Description and Operation
The knock sensor is attached to the cylinder block and senses engine knocking. A knocking vibration from the cylinder block is applied as pressure to the
sensor's piezoelectric element. This vibration pressure is then converted into a voltage signal. The Engine Control Module (ECM) uses this signal to
suppress knocking by retarding ignition timing.