P0325 Knock Sensor 1 Circuit Malfunction (Bank 1 or Single Sensor)

P0325 points to a knock-sensor circuit malfunction for bank 1 or a single-sensor setup. It is usually an input-circuit problem, not proof that the engine is actually knocking.

Code details

Generic OBD-II · P0

System: Ignition / Misfire
Code type: Generic (SAE / ISO controlled)
Standard: SAE J2012 / ISO 15031-6

Diagnostic boundary

A diagnostic trouble code reports that a monitored test failed. It does not prove one specific part is bad, and manufacturer logic can add vehicle-specific conditions.

Do not tune around or ignore a knock-sensor circuit fault; the control module may lose important detonation protection.

Symptoms of P0325

Rough idle, shaking, or a stumble under acceleration.
A flashing check-engine light during an active misfire.
Power loss and higher fuel consumption.

Common causes of P0325

Worn spark plugs, ignition coils, or plug wires.
Fuel-delivery problems — injectors, pressure, or a lean/rich mixture.
Vacuum leaks, low compression, or a mechanical fault in that cylinder.

Useful checks before replacing parts

Inspect knock-sensor wiring, connector condition, shielding, routing, and sensor torque or mounting if service information calls for it.
Check for water intrusion, rodent damage, or harness repairs in the valley or under-intake area on engines where the sensor is buried.
Review timing, fuel quality, and companion codes only after the sensor circuit is proven sound.

Related OBD-II codes

These nearby ignition / misfire entries can help compare wording and pin down the fault area.