OBD-II · Engine and powertrain (P)
P0331
Knock sensor B range/performance
What it means
The signal from knock sensor B (bank 2, or the second sensor on inline engines that have two) is weaker or stronger than expected for the engine speed and load.
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 | incorrect sensor torque or loose sensor |
| 02 | failed knock sensor |
| 03 | wiring or connector fault |
| 04 | loud mechanical noise from the engine |
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