DTC P0327: Knock Sensor Circuit: Description
WARNING: This page is about a different car, the 2002 Oldsmobile Aurora. However, it is still accessible from the selected car via links, so may be relevant.
The Powertrain Control Module (PCM) uses a Knock Sensor (KS) in order to detect engine detonation. The knock sensor produces an AC signal at all engine speeds, and loads. The PCM adjusts to the spark timing that is based on the amplitude and on the frequency of the KS signal. The PCM uses the knock sensor in order to determine the amount of normal engine noise for a wide range of engine speeds and loads. The PCM compares the actual knock sensor signal to the learned noise channel. The PCM uses the noise channel in order to diagnose the knock sensor and the related wiring. If the PCM detects a loss of the noise channel, this DTC will set.