Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
DTC P0325: Knock Sensor Circuit Malfunction
- Turn the ignition switch to ON (II).
- Clear the DTC with the HDS.
- Start the engine. Hold the engine speed at 3,000 rpm without load (A/T in P or N, M/T in neutral) until the radiator fan comes on, then let it idle.
- Hold the engine speed between 3,000-4,000 rpm for at least 10 seconds.
- Check for Pending or Confirmed DTCs with the HDS.
Is DTC P0325 indicated?
YES -Go to step 6.
NO -Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the knock sensor and the ECM/PCM.
- Turn the ignition switch to LOCK (0).
- Jump the SCS line with the HDS.
- Disconnect the knock sensor 1P connector (see KNOCK SENSOR REPLACEMENT ).
- Disconnect ECM/PCM connector C (44P).
- Check for continuity between ECM/PCM connector terminal C42 and body ground.
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there continuity?
YES -Repair short in the wire between the ECM/PCM (C42) and the knock sensor, then go to step 14.
NO -Go to step 11.
- Connect the knock sensor 1P connector terminal to body ground with a jumper wire.
- Check for continuity between ECM/PCM connector terminal C42 and body ground.
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there continuity?
YES -Go to step 13.
NO -Repair open in the wire between the ECM/PCM (C42) and the knock sensor, then go to step 14.
- Replace the knock sensor (see KNOCK SENSOR REPLACEMENT ).
- Reconnect all connectors.
- Turn the ignition switch to ON (II).
- Reset the ECM/PCM with the HDS.
- Do the ECM/PCM idle learn procedure (see ECM/PCM IDLE LEARN PROCEDURE ).
- Hold the engine speed between 3,000-4,000 rpm for at least 10 seconds.
- Check for Pending or Confirmed DTCs with the HDS.
Is DTC P0325 indicated?
YES -Go to step 21.
NO -Go to step 20.
- Monitor the OBD STATUS for DTC P0325 in the DTCs MENU with the HDS.
Does the screen indicate PASSED?
YES -Troubleshooting is complete. If any other Pending or Confirmed DTCs were indicated in step 19, go to the INDICATED DTC'S TROUBLESHOOTING .
NO -If the screen indicates FAILED, check for poor connections or loose terminals at the knock sensor and the ECM/PCM, then go to step 1. If the screen indicates NOT COMPLETED, go to step 18.
- Update the ECM/PCM if it does not have the latest software (see ECM/PCM UPDATE ), or substitute a known-good ECM/PCM (see SUBSTITUTING THE ECM/PCM ).
- Hold the engine speed between 3,000-4,000 rpm for at least 10 seconds.
- Check for Pending or Confirmed DTCs with the HDS.
Is DTC P0325 indicated?
YES -Check for poor connections or loose terminals at the knock sensor and the ECM/PCM. If the ECM/PCM was updated, substitute a known-good ECM/PCM (see SUBSTITUTING THE ECM/PCM ), then go to step 22. If the ECM/PCM was substituted, go to step 1.
NO -Go to step 24.
- Monitor the OBD STATUS for DTC P0325 in the DTCs MENU with the HDS.
Does the screen indicate PASSED?
YES -If the ECM/PCM was updated, troubleshooting is complete. If the ECM/PCM was substituted, replace the original ECM/PCM (see ECM/PCM REPLACEMENT ). If any other Pending or Confirmed DTCs were indicated in step 23, go to the INDICATED DTC'S TROUBLESHOOTING .
NO -If the screen indicates FAILED, check for poor connections or loose terminals at the knock sensor and the ECM/PCM. If the ECM/PCM was updated, substitute a known-good ECM/PCM (see SUBSTITUTING THE ECM/PCM ), then go to step 22. If the ECM/PCM was substituted, go to step 1. If the screen indicates NOT COMPLETED, go to step 22.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.