Parts
$30–80
P0325 — Knock Sensor 1 Circuit — Bank 1
CAUTIONIs it safe to drive? Drive conservatively — the ECM will retard timing to protect the engine, which means reduced power and worse fuel economy until the sensor circuit is repaired.
What P0325 means
The knock sensor listens for abnormal engine vibration (detonation/pinging) so the ECM can pull ignition timing back before damage occurs. A circuit fault means the ECM is flying blind on knock — so it defaults to a conservative, protective timing map.
Most likely causes (in order)
- Knock sensor connector corroded or broken (check wiring first — common failure)
- Knock sensor itself failed (internal open/short)
- Sensor not torqued to spec — too loose gives false reads, too tight cracks the ceramic
- Wiring harness chafed against engine block or heat shield
- Actual engine knock from carbon buildup or wrong fuel octane
Symptoms you might notice
- pinging or knocking under load
- reduced power
- worse fuel economy
- CEL on
What to check first
Before replacing the sensor, wiggle the connector with the engine running and a scanner watching live data — an intermittent signal drop confirms a connector/wiring fault, which is a $5 fix vs. a $40 sensor.
Repair cost & difficulty
Labor
0.5–2 hr
Difficulty
Moderate