Knock Sensor: Testing and Inspection

1999 Chrysler Cirrus L4-2.4L VIN XSECTION 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 sensor generates an AC voltage whose amplitude increases with the increase of 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 600 mVac (5000 rpm). If the output falls outside of this range a DTC will be set.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • You smell fuel, burning insulation, or see smoke.
  • Brakes feel soft, pull hard to one side, or make grinding noises.
  • The engine overheats, stalls repeatedly, or misfires under load.
  • You are missing required tools, torque specs, or safe lifting equipment.
  • You are not confident in the next step or safety outcome.