Inspection Procedure 20 - Engine Knocks

NOTE: Possible causes are: defective knock sensor, improper heat range spark plug or contaminated fuel.

Using scan tool, check for stored Diagnostic Trouble Codes (DTCs). If stored DTCs exist, perform appropriate test procedures for each DTC, and clear DTCs from ECM. If no DTCs exist, go to next step.
Using scan tool, check ignition timing. Ensure ignition is off. Disconnect connector from knock sensor. Knock sensor is located on side of cylinder block, just below intake manifold. Knock sensor contains a 2-pin Gray connector with White and Black/White wires in connector.
Using scan tool, check that ignition timing is now retarded with knock sensor disconnected. Road test vehicle and note if knock still exists.
If knock still exists with knock sensor disconnected, go to next step. If knock does not exist with knock sensor disconnected, check knock sensor circuit. Perform DTC TEST NO. 15.
Check for proper heat range spark plug. Check for contaminated fuel.