P0325: OBD-II code P0325 means the PCM has detected a fault in the bank 1 knock sensor circuit — the engine can't retard timing to prevent detonation.

Symptoms

• Check engine light is on; the PCM retards ignition timing conservatively to protect against knock it can't detect.
• Slight loss of power, especially under load, on hills, or on lower-octane fuel.
• A modest drop in fuel economy because the PCM is running defensive timing without live knock feedback.

Common causes

• A failed knock sensor with an open or shorted internal element — by far the most common cause.
• Damaged wiring or a corroded connector at the sensor, often located under the intake manifold.
• A loose or improperly torqued knock sensor bolt (torque spec matters for accurate readings).

What to do?

Read the live knock signal in scan data during a road test — a healthy sensor shows activity under load. Measure sensor resistance with a DMM (typical spec is around 90k-100k Ω). Replace the sensor if it is out of range. Torque the mounting bolt to spec after installation.