For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provide an overview of each diagnostic category.

### DTC Descriptor

DTC P0325: Knock Sensor (KS) Module Performance

### Circuit/System Description

The knock sensor (KS) enables the engine control module (ECM) to control the ignition timing for the best possible performance while protecting the engine from potentially damaging levels of detonation. The KS produces an AC voltage signal that varies depending on the vibration level during engine operation. The ECM adjusts the spark timing based on the amplitude and the frequency of the KS signal. The ECM receives the KS signal through a signal circuit . The ECM supples a ground circuit to the KS through a low reference circuit . The ECM also supplies a shielded ground circuit to the KS. The ECM learns a KS noise level at idle and uses calibrated values for the rest of the engine speed range. The ECM should monitor a normal KS signal within the noise channel.

### Conditions for Running the DTC

• | DTCs P0106, P0107, and P0108 are not set.

• | The engine speed is more than 1,600 RPM.

• | The engine coolant temperature (ECT) is more than 50°C (122°F).

• | The manifold absolute pressure (MAP) is between 110-50 kPa which is based on engine speed.

• | DTC P0325 runs continuously once the above conditions are met.

### Conditions for Setting the DTC

• | The ECM detects an internal malfunction in the KS circuitry that will not allow for the correct diagnosis of the KS system.

• | The above condition is present for 4 seconds.

### Action Taken When the DTC Sets

DTC P0325 is a Type C DTC.

### Conditions for Clearing the DTC

DTC P0325 is a Type C DTC.

### Reference Information

#### Description and Operation

Knock Sensor (KS) System Description

#### DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

### Circuit/System Testing

1. Ignition ON, observe the DTC information with a scan tool.

⇒ | If DTC P0325 failed this ignition, replace the ECM.

2. If the vehicle passes the Circuit/System Verification Test, then operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records List.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for ECM replacement, setup, and programming