Drive with caution — fix soon.
This code means the computer detected a problem in the bank 2 knock sensor circuit, so it can no longer rely on that sensor to listen for engine knock. It's usually caused by a failed knock sensor, damaged wiring or connectors, or sometimes corrosion at the connection. The fix is typically replacing the knock sensor and repairing any wiring, and it rarely requires major engine work.
$150 – $400
Varies by vehicle and root cause.
Usually yes, for short-term driving. The engine may run a bit more conservatively to protect itself, but it's safe to drive to the shop. Just avoid hard acceleration and get it diagnosed soon.
Most repairs run between $150 and $400, depending on the car. The knock sensor itself is fairly inexpensive, but on some engines it sits under the intake manifold, which adds labor time and cost.
It's moderate. Your car won't break down immediately, but a missing knock sensor signal means the engine can't fine-tune its timing as well, which over time can affect performance and fuel use. It's worth fixing rather than ignoring.
A knock sensor is a small microphone-like device that listens for engine knock or detonation. When it works, the computer can safely advance timing for better power and economy. With P0331, the bank 2 sensor isn't reporting properly, so the computer plays it safe.