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 Descriptors

DTC P0325: Knock Sensor (KS) Module Performance - Non European Emissions
DTC P0325: Knock Sensor (KS) Circuit - European Emissions

### 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 supplies 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) for Euro III Emissions or 66°C (151°F) for Euro IV Emissions.

• | The manifold absolute pressure (MAP) is between 10-50 kPa which depends on engine speed.

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

### Conditions for Setting the DTC

#### DTC P0325 - Non European Emissions

The control module has detected an internal circuitry fault.

#### DTC P0325 - European Emissions

The ECM detects an incorrect KS signal for more than 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 Verification

⇒ | If DTC P0325 failed this ignition, for a Non European Emissions system, replace the ECM.

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.

### Circuit/System Testing - European Emissions Only

Important: If the knock sensor lead is damaged in any way, replace the knock sensor.

1. Ignition OFF, disconnect the harness connector of the KS sensor.
2. Ignition ON, connect a test lamp between the signal circuit of the KS and ground. The test lamp should not illuminate.

⇒ | If the test lamp illuminates, test the signal circuit for a short to voltage. If the circuits/connections test normal, replace the ECM.

3. Ignition ON, connect a test lamp between the signal circuit of the KS and B+. The test lamp should not illuminate.

⇒ | If the test lamp illuminates, test the signal circuit for a short to ground. If the circuits/connections test normal, replace the ECM.

4. Ignition OFF, connect a DMM between the signal circuit and the low reference circuit.
5. Test for 90-110K ohms between the signal circuit and the low reference circuit of the KS.

⇒ | If the resistance is not within the specified range, test the circuits for an open/high resistance. If the circuits/connections test normal, replace the ECM.

6. If all circuits/connections test normal, replace the KS sensor.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for engine control module replacement, setup, and programming