Detection Condition
WARNING: This page is about a different car, the 2002 Mazda Tribute. However, it is still accessible from the selected car via links, so may be relevant.
DTC P0325 indicates Knock Sensor (KS) malfunction.
DTC P0326 indicates knock sensor has detected vibrations (voltage generated is based on this vibration) relative with engine speed that is outside a calibrated level.
A tuned accelerometer on engine that converts engine vibration to an electrical signal. PCM uses this signal to determine presence of engine knock and retard ignition timing as necessary.