DTC P0325: Knock Sensor Module Circuit: Description
WARNING: This page is about a different car, the 2002 Pontiac Montana, 2002 Oldsmobile Silhouette, and 2002 Chevrolet Venture. However, it is still accessible from the selected car via links, so may be relevant.
The knock sensor (KS) produces an alternating current voltage at all engine speeds and loads. The Powertrain Control Module (PCM) then adjusts the spark timing based on the amplitude and on the frequency of the KS signal. The PCM uses the KS signal in order to calculate the average voltage and assigns a voltage value. The PCM checks the KS and the related wiring by comparing the actual knock signal to the assigned voltage range. A normal KS signal should remain out of the assigned voltage range. This Diagnostic Trouble Code (DTC) will set if the PCM malfunctions in a manner that will not allow proper diagnosis of the KS system.