P0331 — Knock Sensor 2 Circuit Malfunction (Bank 2)
Drive with caution — fix soon.
What P0331 means
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.
Common symptoms
- Check engine light is on
- Slight loss of power or sluggish acceleration
- Reduced fuel economy
- Occasional engine knocking or pinging sound
- Engine may feel less responsive under load
Common causes
- Failed knock sensor on bank 2
- Damaged or corroded wiring to the sensor
- Loose or corroded electrical connector
- Broken sensor mounting or improper torque
- Faulty engine control module (rare)
Typical repair cost
$150 – $400
Varies by vehicle and root cause.
Frequently asked questions
Can I keep driving with a P0331 code?
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.
How much does it cost to fix a P0331 code?
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.
Is a P0331 code serious?
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.
What is a knock sensor and why does it matter?
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.