Knock Sensor: Testing and Inspection

Typical Knock Sensor Signal:

DYNAMIC TESTING PROCEDURE:

NOTE: Knock sensors can be tested dynamically with the use of an oscilloscope only.

1. Turn ignition "ON".
2. Probe terminals #1 and #2 at knock sensor.
3. Tap on the engine block, near the sensor, with a small hammer or wrench.
4. Oscilloscope should show a wave pattern similar to the one shown in the image.
a. If pattern is correct, knock sensor is working properly.
b. If pattern is incorrect, replace and retest with new sensor.
5. Turn ignition "OFF" and disconnect all test equipment.

Knock Signal Display:

Knock Sensor Signal Display Engine Running