P0325 on Subaru
Knock Sensor 1 Circuit Malfunction (Bank 1)
P0325 on Subaru vehicles indicates knock sensor 1 circuit malfunction (bank 1). Au7o has documented this code across 1 Subaru model — most commonly on Forester. This code indicates a fault in the knock sensor 1 circuit on Bank 1. The knock sensor listens for the vibrations of detonation (pinging/spark knock) and lets the computer retard ignition timing to protect the engine. When the sensor's signal is missing, out of range, or the circuit is open/shorted, P0325 sets. With knock detection compromised, the computer may run more conservative timing, causing reduced power and slightly lower fuel economy, and the engine is less protected against damaging knock. Typical repair costs on Subaru range from $80 to $250, depending on the specific model and root cause.
Common Causes of P0325
- •Failed knock sensor
- •Corroded or loose knock sensor connector
- •Damaged, open, or shorted sensor wiring
- •Improperly torqued or loosely mounted sensor
- •Moisture or corrosion in the connector
- •Wiring harness chafing near the engine
- •Faulty PCM/ECM (rare)
P0325 on Subaru by Model
Subaru Forester(1 issue)
- Knock Sensor Housing Cracking — P0325 and Permanent Timing Retard1998-2005
The single knock sensor bolted to the top of the EJ block on SF- and early SG-generation Foresters has a brittle plastic/resin housing that cracks after years of heat cycling directly on the block. Once cracked, the piezo element's circuit reads out of range and the ECU sets P0325. The car keeps running, but the ECU falls back to a conservative safe ignition map: owners report noticeably reduced power, sluggish throttle response and a measurable drop in fuel economy. The failure is common enough that many independent shops replace the sensor on any high-mileage EJ Forester showing that code without further diagnosis. A secondary cause is the sensor wiring harness chafing or the connector corroding, so the harness should be inspected before condemning the sensor.
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What does P0325 mean on Subaru?▼
P0325 stands for "Knock Sensor 1 Circuit Malfunction (Bank 1)." This code indicates a fault in the knock sensor 1 circuit on Bank 1. The knock sensor listens for the vibrations of detonation (pinging/spark knock) and lets the computer retard ignition timing to protect the engine. When the sensor's signal is missing, out of range, or the circuit is open/shorted, P0325 sets. With knock detection compromised, the computer may run more conservative timing, causing reduced power and slightly lower fuel economy, and the engine is less protected against damaging knock. On Subaru specifically, this code is documented across 1 model.
What causes P0325 on Subaru vehicles?▼
Common causes on Subaru: Failed knock sensor, Corroded or loose knock sensor connector, Damaged, open, or shorted sensor wiring, Improperly torqued or loosely mounted sensor, Moisture or corrosion in the connector. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0325 on a Subaru?▼
Repair costs on Subaru range from $80 to $250, depending on the specific model and root cause.
Which Subaru models have P0325 documented?▼
Au7o has documented P0325 on 1 Subaru model: Forester.