Knock Sensor: Testing and Inspection

MOUNTING

- Check that the knock sensor mounting bolt torque is within specification (engine cold, 15 - 18 ft. lbs.). CAREFULLY, loosen and retorque as necessary.

- The harness should be checked for continuity and proper routing, Refer to VAG 1598 Pin Out Box/ Electrical Checks steps 24 & 27.

OSCILLOSCOPE TEST

- With the engine "OFF", disconnect the knock sensor harness connectors.

- Connect the positive lead of an oscilloscope to terminal #1 and the negative lead to terminal #2 of the knock sensor I. Refer to scope manufacture instructions.

- Start the engine and warm to operating temperature.

Oscilloscope Display:

- Operate the engine at 5000 rpm and observe the scope pattern.

- Repeat steps 5 - 8 for knock sensor II.

- If the pattern does not appear similar to the example, replace the knock sensor.