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

P0325 is triggered when the ECU detects an abnormal voltage or a loss of signal from Knock Sensor 1. The knock sensor is typically a piezoelectric transducer that monitors vibrations caused by detonation or pre-ignition. The ECU uses this signal to fine-tune ignition timing. If the signal is missing or out of its calibrated range (typically between 0.5V and 4.5V), the ECU will default to a 'safe' ignition map, retarding the timing to prevent engine damage, resulting in reduced performance.