P0325 Code: Meaning, Causes, and Symptoms | OBD2 Codes

P0325 – Knock Sensor Circuit Malfunction


P0325: DIY Repairing Video Tutorial


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P0325 Possible Causes

Faulty Knock Sensor

Knock Sensor circuit poor electrical connection

Knock Sensor harness is open or shorted

Faulty Engine Control Module (ECM)

P0325 Possible Symptoms

Engine Light ON (or Service Engine Soon Warning Light)

Possible Lack/Loss of Power


A knocking vibration from the cylinder block is sensed as vibrational pressure by the Knock Sensor. This pressure is converted into a voltage signal and sent to the Engine Control Module (ECM). The ECM uses this signal to retard the ignition timing and protect the engine from this damaging pre-ignition. Engine knock occurs within a specific frequency range. The Knock Sensor, located in the engine block, cylinder head, or intake manifold, is tuned to detect that frequency. Inside the knock sensor is a piezoelectric element. Piezoelectric elements generate a voltage when pressure or vibration is applied to them. The piezoelectric element in the Knock Sensor is tuned to the engine knock frequency. The vibration from the engine knocking vibrates the piezoelectric element generating a voltage. The voltage output from the Knock Sensor is highest at this time.