Knock Sensor: Testing and Inspection

The engine knock sensor is affected by a number of factors. A few of these are:
- Ignition Timing
- Cylinder Pressure
- Fuel Octane etc

The knock generates an AC voltage whose amplitude increases with increasing engine knock. The knock sensor can be tested with a digital voltmeter.

The RMS voltage starts at about 20mVAC (at about 700 rpm) and increases to approximately 600mVAC (5,000 rpm).

If the output falls outside of this range a DTC will be set.