OBD-II · Engine and powertrain (P)
P0325
Knock sensor circuit fault
What it means
The ECU cannot trust the knock sensor signal used to protect the engine.
Symptoms
- reduced power and slower acceleration (the ECU retards ignition as a precaution)
- higher fuel consumption
- engine warning light
Likely causes, most likely first
| No. | Cause |
|---|---|
| 01 | failed knock sensor |
| 02 | open or shorted wiring |
| 03 | loose or corroded connector |
| 04 | sensor ground or shielding fault |
| 05 | ECU input fault |
What to check, step by step
- 01Inspect the sensor connector and wiring, which often run under the intake manifold
- 02Check the sensor is tightened to the specified torque: knock sensors are torque-sensitive
- 03Measure the sensor resistance and check the wiring to the ECU for opens, shorts and damaged shielding
- 04Look for real engine knock or loud mechanical noise if the sensor and wiring are fine
- 05Replace the sensor, cleaning the mounting surface and using the correct torque