P0325 on a Subaru: Causes, Fixes & Repair Cost

🟠 Moderate severity · drivable

You can drive, but the engine runs with reduced timing protection and fuel economy may drop, so have the knock sensor checked soon.

What P0325 means on a Subaru

On a Subaru, P0325 means the knock sensor on bank 1 is not sending a proper signal to the engine computer. The sensor detects engine knock so the computer can adjust ignition timing; without it the engine loses that protection.

Is P0325 common on Subarus?

P0325 is seen on Subarus with the flat-four engines, especially Outback, Forester, Impreza, and Legacy. The knock sensor sits on top of the engine block and is fairly easy to reach, and sensor failure or a damaged connector is the usual cause.

Commonly reported on: Outback, Forester, Impreza, Legacy.

Symptoms

Check engine light on
Reduced fuel economy
Engine pinging under load
Slight loss of power

Common causes

most common: Failed knock sensor
common: Damaged or corroded sensor connector
common: Chafed or damaged sensor wiring harness
rare: Engine computer issue

How to fix it

Fix	DIY?	Typical cost
Replace the knock sensor	Yes	$100–350
Repair the wiring harness near the sensor	Mechanic	$100–300
Clean and reseat the sensor connector	Yes	$20–60

Frequently asked questions

Can I drive a Subaru with a P0325 code?

Yes, in most cases. The engine still runs, but without knock protection it may ping under load, and fuel economy can drop, so get it checked soon.

What usually causes P0325 on a Subaru?

A failed knock sensor or a damaged connector, common on Outback, Forester, Impreza, and Legacy models. On Subarus the sensor sits on top of the engine and is easy to reach.

How much does it cost to fix P0325 on a Subaru?

Replacing the knock sensor typically runs $100–350 with parts and labor because it is easy to access. A wiring repair is usually $100–300.