Knock Sensor: Testing and Inspection

2000 Hyundai Tiburon L4-2.0LSECTION Testing and Inspection



The knock sensor is attached to the cylinder block and senses engine knocking conditions.

A knocking vibration from the cylinder block is applied as pressure to the piezoelectric element. This vibrational pressure is then converted into a voltage signal which is delivered as output. If engine knocking occurs, ignition timing is retarded to suppress it.

Circuit Diagram:






Harness Inspection Procedure (Steps 1 - 2):






SENSOR INSPECTION




1. Disconnect the knock sensor connector.
2. Measure resistance between the terminal 2 and 3.

Standard value about 5 MOhms [at 20 °C (68 °F)]

3. If the resistance is continual, replace the knock sensor.

Tightening torque
knock sensor: 16 - 28 Nm (160 - 250 kg.cm, 11.8 - 18.4 lb.ft)

4. Measure the capacitance between the terminal 2 & 3.

Standard value: 800 - 1600 pF

Troubleshooting Procedures:






TROUBLESHOOTING HINTS
When knock sensor signal is abnormally low.
RENDER: 1.0x

NO RELATED

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When to See a Mechanic

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

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