What this code means
P0328 generally means the PCM may be seeing a knock sensor signal that is higher than expected.
What the vehicle may do
- The vehicle may turn on a warning light.
- The concern can be intermittent.
- Driveability symptoms may be limited or may vary by condition.
Possible fault areas
- Possible knock sensor concern.
- Possible poor connector contact or loose terminal at the knock sensor or ECM.
- Possible open in the KNOCK or KSGND circuit.
- Possible PCM software or PCM-side concern.
Diagnostic path
Open and frame the fault
On this 2010 to 2015 Honda Civic with the 1.8 gas engine, P0328 is a knock sensor circuit high voltage fault. In plain terms, the PCM may be seeing the knock sensor signal higher than expected. The driver may only notice a warning light, and the problem can be intermittent. Broadly, this may come from the knock sensor itself, a poor connector or loose terminal, an open in the KNOCK or KSGND circuits, or a PCM software or PCM-side issue. Start with the basic system checks, then follow a structured electrical diagnosis instead of guessing at parts.
Verify P0328 first
First, verify the failure. Turn the ignition switch to ON (II), or use the engine start-stop button to select ON mode. Clear the DTC with the HDS. Then turn the ignition switch to LOCK (0), or select OFF mode. Turn it back to ON (II), or ON mode, and check for pending or confirmed DTCs with the HDS. If P0328 comes right back, the failure is duplicated and you move into circuit testing. If P0328 is not indicated, treat it as intermittent for now. The system is OK at this moment, so check for poor connections or loose terminals at the knock sensor and the ECM. If captured operating data is available for this code, try to reproduce the same conditions before going deeper.
Check sensor-side voltage between the two knock sensor wires
With the failure duplicated, turn the ignition switch to LOCK (0), or select OFF mode. Jump the SCS line with the HDS, then disconnect the knock sensor 2P connector. Turn the ignition back to ON (II), or ON mode. Now measure voltage between knock sensor connector No. 1, the BLK wire, and knock sensor connector No. 2, the WHT wire. You are checking the KNOCK and KSGND sides with the connector disconnected. The decision point is about 5.0 V. If you have about 5.0 V here, the diagnostic path calls for replacing the knock sensor. If you do not have about 5.0 V, continue to the next voltage check.
Separate the KNOCK line from the ground side
Next, keep the ignition in ON (II), or ON mode, and measure the KNOCK line directly to body ground. Put one lead on knock sensor 2P connector No. 2, the WHT wire, and the other lead on body ground. Again, the decision point is about 5.0 V. If you see about 5.0 V, the KNOCK line has voltage and the next check is the KSGND side for an open. If you do not see about 5.0 V, move to the KNOCK wire open check.
If the KNOCK line has voltage, check KSGND for an open
For the KSGND open check, turn the ignition switch to LOCK (0), or select OFF mode. Jump the SCS line with the HDS and disconnect PCM connector C, the 51P connector. Install a jumper between knock sensor 2P connector No. 1, the BLK wire, and body ground. Then check continuity between PCM connector C, terminal No. 28, the BLK wire, and body ground. If there is continuity, the KSGND wire is OK. At that point, update the PCM if it does not have the latest software, or substitute a known-good PCM. If P0328 goes away after the update, troubleshooting is complete. If P0328 goes away with the known-good PCM substituted, replace the original PCM. If there is no continuity, repair the open in the KSGND wire between PCM C28 and the knock sensor.
If the KNOCK line did not show voltage, check KNOCK for an open
For the KNOCK wire open check, turn the ignition switch to LOCK (0), or select OFF mode. Jump the SCS line with the HDS and disconnect PCM connector C, the 51P connector. Install a jumper between knock sensor 2P connector No. 2, the WHT wire, and body ground. Then check continuity between PCM connector C, terminal No. 29, the WHT wire, and body ground. If there is continuity, the KNOCK wire is OK. Update the PCM if it does not have the latest software, or substitute a known-good PCM. If P0328 goes away after the update, troubleshooting is complete. If P0328 goes away with the known-good PCM substituted, replace the original PCM. If there is no continuity, repair the open in the KNOCK wire between PCM C29 and the knock sensor.
Close and takeaway
The key with P0328 is to prove whether the fault is present, then use the voltage checks to split sensor, KSGND, KNOCK, and PCM-side possibilities. Do not jump ahead: the path changes based on about 5.0 V and continuity at the exact points in the circuit. Once the repair path is completed, verify the repair and confirm the code stays gone. For more diagnostic training, visit stepdiagnostics.com.
Final check
This diagnosis may be best handled as an electrical circuit split: verify the code, check the sensor-side voltage, then separate the KNOCK and KSGND paths before considering PCM-side action.
For more guided automotive diagnostics, visit STEP Diagnostics.
