Knock Sensor: Testing and Inspection

The engine knock sensor is affected by a number of factors. A few of these are: ignition timing, cylinder compression, fuel octane, etc. The knock sensor generates an AC voltage whose amplitude increases with an increase in engine knock.


Knock sensor can be tested using 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 this range a DTC is set.