Code P0325, Knock Sensor Error (Single Sensor): Notes

Knock sensor is used to detect engine detonation and allow PCM to retard Ignition Control (IC) timing based on signal being received. Circuitry within knock sensor causes PCM's supplied 5 volts signal to be pulled down, so that under a no knock condition circuit would measure about 2.5 volts DC. Knock sensor produces an AC signal which rides on 2.5 volts DC voltage. Amplitude and signal frequency is dependent upon knock level.

If circuit becomes open or shorted to ground, voltage will either become greater than 3.5 volts or less than 1.5 volts respectively.

Code P0325 will set when the following conditions are present.

• Voltage on signal circuit becomes greater than 3.5 volts or less than 1.5 volts.
• Either condition is present for 20 seconds.
  NOTE: Test numbers refer to numbers on diagnostic chart.

1. If Code P0325 is detected, PCM will retard spark timing. If an audible knock is heard from engine, repair internal engine problem. Normally no knock should be detected at idle.
2. PCM applies 5 volts through a pull-up resistor which should be present at knock sensor terminal.
3. Determines if knock sensor is faulty or if knock sensor portion of PROM is faulty.