Knock Sensor Module: Description and Operation

Ignition Knock Regulation

If a cylinder develops ignition knock (detonation), the control unit will "hear" this through the knock sensor. The engine control unit will then retard the ignition timing by one step of 2.6°. The engine control unit will then check to see if knocking has stopped. If knocking continues, the timing can be retarded two additional steps of 2.6° each for a total of 7.8°.

Once ignition knock has stopped, the timing will be advanced back to its predetermined value in smaller steps of 1.3°.

Also, to prevent errors, the knock sensor signal will only be processed when the engine is in the operating range where ignition knock can occur. These are:
^ Engine coolant temperature above 70°C (158°F)
^ Intake manifold pressure above 0.7 bar (absolute)
^ Idle switch open