Fault codeP0331

SEVERE

Knock Sensor 2 Circuit Range/Performance (Bank )

What this code means

Knock Sensor 2 Circuit Range/Performance (Bank ).

P0331 is a generic code: it means the same thing on every make. P0331 belongs to family P03xx — Ignition and misfire. Its page explains how to read a code and groups all its codes by part.

Type of fault

The signal stays within its electrical limits, but its value is not plausible: it does not match what the control unit expects given the other sensors. The sensor may be drifting with age, but it may also be faithfully measuring a real mechanical problem — a leak, a blockage, an air leak. Replacing the sensor without checking does not always clear the fault.

Knock sensor

The knock sensor is a small microphone bolted to the engine block. It listens for the sharp vibration of knock, abnormal combustion that can damage pistons. When it hears it, the control unit retards the ignition timing on the cylinder concerned.

What you notice

Usually little: the control unit retards ignition as a precaution, so the engine may lack power and consume more. Audible pinging under load points to real knock.

How to check it

The sensor must be tightened to the right torque on a clean surface: too loose or too tight, it hears badly. Check its connector and wiring, often under the intake manifold. In Klaro, a timing advance that stays very low under load hints that the control unit is retarding ignition.

Watch it live in Klaro

With an OBD2 adapter plugged in, these live readings show the part at work, when your car reports them:

Timing advance
Engine RPM

What to do

Have it checked promptly. A misfire sends unburnt fuel into the exhaust and destroys the catalytic converter within a few dozen kilometres. If the light is flashing, stop driving.

Clearing a code switches the light off but repairs nothing: if the fault remains, the code comes back. Clearing a fault code yourself →

How to read this code

PPowertrain
0standardised code
3Ignition and misfire
31P0331