Fault codeP0325

SEVERE

Knock Sensor 1 Circuit Malfunction (Bank 1 or Single Sensor)

What this code means

Knock Sensor 1 Circuit Malfunction (Bank 1 or Single Sensor).

“Bank 1” is the side of the engine that holds cylinder number 1; “Bank 2” only exists on V and flat engines. An in-line engine has a single bank.

P0325 is a generic code: it means the same thing on every make. P0325 belongs to family P03xx — Ignition and misfire. Its page explains how to read a code and groups all its codes by part.

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.

Symptoms

Moderate loss of power and higher consumption, sometimes a metallic pinking under acceleration. Without a knock sensor signal, the control unit retards ignition for safety: the engine is protected, but held back. The code concerns the sensor's electrical circuit, not actual knocking.

Common causes

Faulty knock sensor
Corroded connector or cut wire — the sensor is often under the intake manifold, exposed to heat
Sensor loose or torqued wrongly, so it no longer hears anything
Less often: genuine mechanical knock from low-octane fuel or an overheating engine

How to diagnose it

Locate the sensor on the block and inspect its connector and wire, often made brittle by heat. Measure its resistance and compare with the manufacturer's figures; tapping the block lightly next to it, a healthy sensor produces a voltage visible on an oscilloscope.

If the sensor was removed recently, check its torque: too much or too little, and it does not work.

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 →

Repair cost

Sensor: €30 to €120. Labour can exceed the part when the intake manifold has to come off: €100 to €300.

How to read this code

PPowertrain
0standardised code
3Ignition and misfire
25P0325