P0325

DTC P0325

CIRCUIT DESCRIPTION
The knock sensor (KS) system enables the powertrain control module (PCM) to control the ignition timing for the best possible performance while protecting the engine from potentially damaging levels of detonation. The KS is located on the intake side of the engine block. The KS produces an AC voltage signal that varies depending on the vibration level during engine operation. The PCM adjusts the spark timing based on the amplitude and the frequency of the KS signal. The PCM receives the KS signal through a signal circuit. The KS ground is supplied by the PCM through a low reference circuit. The PCM learns a minimum KS noise level at idle and uses calibrated values for the rest of the RPM range. The PCM should monitor a normal KS signal within the noise channel. If the PCM malfunctions in a manner that will not allow proper diagnosis of the KS system, this DTC sets.

CONDITIONS FOR RUNNING THE DTC
- DTCs P0101, P0102, P0103, P0116, P0117, P0118, P0335, P0340, P1114, and P1115 are not set.
- The engine speed is between 1,000-2,500 RPM.
- The throttle angle is more than 10 percent.
- The engine load is more than 40 percent.
- The engine coolant temperature (ECT) is more than 60°C (140°F).
- The maximum spark retard is less than 15 degrees.
- The system voltage is more than 9 volts.
- The engine run time is more than 30 seconds.

CONDITIONS FOR SETTING THE DTC
The PCM detects a malfunction in the KS diagnostic circuitry that will not allow proper diagnosis of the KS system.

ACTION TAKEN WHEN THE DTC SETS
- The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
- The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

CONDITIONS FOR CLEARING THE MIL/DTC
- The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
- A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
- A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
- Clear the MIL and the DTC with a scan tool.

TEST

Steps 1 - 5: