Rep Power: 0

01 Civic LX....I just had the head gasket replaced and a valve job done. The CEL came on and it's the knock sensor. I did a search here but didn't come up with much. The engine sounds great, runs great. CEL won't clear. What next? Can I test the knock sensor? I would prefer not to just start throwing money at this thing Thanks

 
Rep Power: 234

Knock sensor is in the back of the engine, above the oil filter.

1. With the ignition OFF, disconnect the knock sensor.

2. Turn the ignition to ON (II) and measure voltage from the red/blue wire to body ground. (wire side, not sensor side)

Is there about 5V?

YES- step 6

NO- step 3

3. Measure voltage from ECM/PCM connector A9 (red/blue wire) to body ground.

Is there about 5V?

YES- Repair open in the red/blue wire between the ECM/PCM and the knock sensor.

NO- step 4

4. Turn the ignition to OFF and disconnect ECM/PCM connector A.

5. Check for continuity (ohms)from terminal A9 (red/blue wire) to body ground.

Is there continuity?

YES- Repair open in the wire between the ECM/PCM and the knock sensor.

NO- Update or replace the ECM/PCM

6. Replace the sensor and reset the ECM/PCM

Is P0325 still indicated?

YES- Update or replace the ECM/PCM
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If you find an open in the circuit look for loose wires at the connector(s) or a broken/pinched wire. If you can't find it then just run a new wire.

ECM/PCM connector A is the bottom connector when looking at the ECM/PCM. The ECM/PCM is behind the glovebox. Once you have the glovebox it's this connector:


To reset the ECM/PCM: With the ignition OFF, remove the #6 fuse in the under-hood fuse box for more than 10 seconds

* If you see any yellow wires by themselves don't mess with them or you might set off the airbags.