What does code P0325 mean on a Subaru and is it safe to drive?
P0325: Knock Sensor 1 Circuit Malfunction (Bank 1). Here's what it means on your Subaru, what usually causes it, what repairs typically cost, and how safe it is to keep driving.
What this code means
The PCM isn't receiving a valid signal from knock sensor 1. Without knock feedback, the PCM retards ignition timing as a safety measure, reducing power and economy.
Common causes for your Subaru
- Failed knock sensor
- Corroded or broken wiring/connector at the sensor
- Actual engine knock from carbon buildup or low-octane fuel
Symptoms
- Check Engine Light
- Reduced power and fuel economy (PCM retards timing)
- Possible audible knock or ping under load
Typical fixes
- Replace knock sensor
- Repair wiring and connector
- Use correct octane fuel and address carbon buildup
Repair cost range
For a Subaru, repairs for P0325 often fall between $150 and $500, depending on the cause and whether you use OEM or aftermarket parts. Labor rates vary by location.
Known issues on Subaru
Subaru P0325 on EJ25 SOHC engines is often a wiring harness issue—the knock sensor harness runs near the downpipe and exhaust, causing heat damage to the insulation over time. Inspect the entire harness length from sensor to PCM connector. On EJ257 turbocharged (WRX STI), a non-functional knock sensor is a critical issue—the Subaru ECU retards timing significantly when knock is detected under boost, and if the sensor is dead, the engine is unprotected from detonation. Fix immediately on turbocharged applications.
Most commonly affected models