Knock sensors, function - GF15.12-P-4101-02KE

Fig 1: Identifying Knock Sensors Oscilloscope Signals

Any vibrations which occur are converted with the aid of the piezo ceramic into electrical signals.

Piezo-electric effect: If a mechanical force acts on a crystal, electrical voltages are produced.

Knock sensor signals may also indicate engine damage, e.g. increased engine noise resulting from a widened piston groove.