| CAUTION | If ECM replacement is instructed in following testing, always ensure ECM connectors and ground circuits are okay. If either are suspect, repair and repeat testing to confirm ECM malfunction. |
Note. For component location, see appropriate illustration in THEORY & OPERATION article.
Circuit Description
Knock sensor generates voltage when engine block vibrates due to knocking. DTC is set when there is no knock sensor signal to ECM when engine speed is 1200 RPM or more. ECM will operate in fail-safe mode if DTC P0325 is set. Possible causes are
- Knock sensor circuit is open or shorted.
- Defective or loose knock sensor.
- Defective ECM.
Diagnostic Aids
Normal mode vibration frequency of knock sensor is 12.5 kHz. Using scan tool, read FREEZE FRAME data. Freeze frame data records engine conditions when malfunction is detected.