P0331: Knock/Combustion Vibration Sensor B Circuit Range/Performance
What to do
Expect reduced performance. An audible rattle from the engine bay is worth reporting.
What this code means
Sensor B's signal — the bank 2 sensor — is electrically valid but implausible. As with bank 1, genuine mechanical noise in the knock frequency band will set this honestly — a loose bracket or heat shield on that side of the engine is worth checking before the sensor is replaced.
Likely causes
Start here
- Faulty knock sensor · moderate
- Loose heat shield or bracket producing noise · easy
- Incorrect knock sensor mounting torque · moderate
Less common
- Low octane or poor quality fuel · easy
- Carbon deposits on intake valves · specialist
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
Be the first to write this up
Nothing posted about this yet. Whatever you found is worth writing down — even a dead end saves someone the same afternoon.
What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
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