P0331
Knock/Combustion Vibration Sensor B Circuit Range/Performance
Ignition / knock sensor
Generic OBD-II
Medium
What it means
P0331 means the second knock sensor's signal is outside the expected range. The knock sensor lets the computer detect engine "knock" and pull ignition timing to protect the engine. Contrary to some templated descriptions, this code does not cause a no-start — it usually just costs a little power and economy until repaired.
Medium
Can I keep driving? Safe to drive short-term; the engine may retard timing for protection, giving slightly less power and economy, but it won't stall or fail to start from this code.
Common symptoms
What you'll notice
- Check-engine light on
- Slightly reduced power or acceleration (timing pulled for safety)
- Small drop in fuel economy
- Possible pinging under hard acceleration if knock goes undetected
Common causes
Most likely first
- Faulty knock sensor BLikely
- Open, shorted, or chafed wiring in the sensor circuitCommon
- Loose or corroded electrical connectorCommon
- Failed engine control module (rare)Less often
How to diagnose & fix
Work through it in order
- Read freeze-frame data and confirm the code is knock sensor B (bank 2).
- Inspect the knock sensor connector and wiring for damage or corrosion.
- Check the sensor's resistance and signal against manufacturer spec; ensure the mounting bolt is torqued (a loose sensor gives false readings).
- Replace the knock sensor if it's out of spec with good wiring. Clear and re-test.
FAQ
Quick answers
Is it safe to drive with P0331?+
Yes, short-term. The engine may run slightly softer because timing is retarded for protection, but this code alone won't leave you stranded. Fix it to restore full power and economy.
Can I just clear P0331?+
It will clear, but returns until the knock sensor or its wiring is repaired.
Related codes
Often seen with P0331
Read & clear P0331 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX