P0326 - Knock Sensor 1 Circuit Range/Performance (Bank 1 or Single Sensor)

P0326 is an OBD-II generic code that indicates the Engine Control Module (ECM) has detected a signal from Knock Sensor 1 that is outside the expected range or is not performing correctly. The knock sensor is a piezoelectric sensor that monitors engine vibrations associated with pre-ignition or spark knock. The ECM uses this feedback to retard ignition timing to prevent engine damage. When the ECM detects a signal that doesn't correlate with engine speed and load data, it triggers P0326. This often results in reduced engine power as the ECM defaults to a conservative timing map.