P0325: Knock sensor 1 circuit fault (bank 1 or single sensor)

What P0325 means

The knock sensor is bolted to the engine block and works like a microphone: it picks up the vibration of knock (detonation, fuel burning at the wrong moment and hammering the pistons). When it hears it, the ECU retards the ignition to protect the engine. This code points to a fault in the sensor’s electrical circuit (wire, connector or sensor). It is sensor 1, on bank 1, or the only one if the engine has just one.

Most common causes

• Loose, dirty or corroded sensor connector
• Broken or chafed sensor wire (often routed under the intake manifold)
• Sensor not tightened properly to the block
• Failed knock sensor
• ECU fault (rare)

Symptoms

• Less power, especially under hard acceleration
• Slightly higher fuel consumption
• Engine warning light on
• Sometimes no noticeable symptoms

Can you drive with P0325?

With care You can drive, as the ECU usually retards the ignition as a precaution, but the engine is less protected if real knock occurs. Avoid working it hard and get it checked soon.

How to check it

If your scan tool shows knock retard, watch it live: if it sits at maximum even though the engine sounds fine, the ECU has gone into protection mode because of the sensor fault.

How to read and clear P0325 with Final OBD

Plug an OBD2 scanner in under the steering wheel, switch the ignition on and open Final OBD. Under Faults you’ll see P0325 with this same explanation and whether it’s confirmed, pending or permanent.

With Free you read this code with its short description for nothing, and clear it if the engine stores it over standard OBD. With Pro you get the full explanation, how the car was running when it was logged (revs, temperature, load) and clearing in every control unit.

Clearing the code only turns the light off: if the cause is still there, it comes back. Clear it once it’s fixed, and not right before the ITV. It’s all in how to read and clear fault codes and in the ITV and OBD.

Similar codes

• P0316 Misfire detected on start-up (first 1000 revolutions)
• P0320 Engine speed input (ignition or distributor): circuit fault
• P0321 Ignition or distributor engine speed signal out of range
• P0322 No ignition or distributor engine speed signal
• P0326 Knock sensor 1 signal out of range (bank 1 or single sensor)
• P0327 Knock sensor 1 circuit low input (bank 1 or single sensor)
• P0328 Knock sensor 1 circuit high input (bank 1 or single sensor)
• P0330 Knock sensor 2 circuit fault (bank 2)
• P0300 Random or multiple cylinder misfire
• P0301 Misfire detected in cylinder 1
• P0302 Misfire detected in cylinder 2
• P0303 Misfire detected in cylinder 3

P0325 is a generic code, so it means the same on any make, for example on Alfa Romeo, Dacia, Kia, Opel / Vauxhall, Toyota, Škoda. See what Final OBD does on your car in makes and models.