Knock Sensor: Testing and Inspection

KNOCK SENSOR
The knock sensor is attached to the side of the cylinder block to sense engine knocking. 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 relayed to the ECM. If engine knocking occurs, ignition timing is retarded to suppress it.

Circuit Diagram:

HARNESS INSPECTION PROCEDURE

SENSOR INSPECTION
1. Disconnect the knock sensor connector and measure resistance between terminals 1 and 2.
Standard value : about 5 Mohm

2. If the resistance is continuous, replace the knock sensor.

Tightening torque
Knock sensor : 16 - 25 Nm (160 - 240 kg.cm, 11.8 - 18.4 lb.ft)

3. Measure the capacitance between terminals 1 and 2.
Standard value : 800 - 1600 pF