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 provides an overview of each diagnostic category.

### DTC Descriptor

DTC P0325 00: Knock Sensor Circuit
DTC P0327 00: Knock Sensor Circuit Low Voltage
DTC P0328 00: Knock Sensor Circuit High Voltage

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Knock Sensor Signal | P0327 00 | P0325 00 | P0328 00 | P0326 00
Low reference | P0327 00 | -- | P0328 00 | P0326 00

### Circuit/System Description

The knock sensor system 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 knock sensor 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 knock sensor signal. The ECM receives the knock sensor signal through a signal circuit and a low reference circuit. The ECM learns a minimum knock sensor noise level at idle and uses calibrated values for the rest of the RPM range. The ECM should monitor a normal knock sensor signal within the noise channel.

### Conditions for Running the DTC

#### P0325 00

This DTC runs continuously when

• | The engine speed is greater than 700 to 2500 RPM.

• | The airflow into the engine is greater than 40 mg/cylinder.

• | The engine run time is greater than 1 s.

• | This DTC runs continuously within the enabling conditions.

• | DTCs P0325 00 runs continuously once the above conditions are met..

#### P0327 00, P0328 00

• | The engine speed is between 600 to 8500 RPM.

• | DTCs P0327 00 and P0328 00 run continuously once the above condition is met.

### Conditions for Setting the DTC

#### P0325 00

The ECM detects the knock sensor signal circuit is open for greater than 5 s.

#### P0327 00

The ECM detects the knock sensor signal circuit is shorted to ground for greater than 5 s.

#### P0328 00

The ECM detects the knock sensor signal circuit is shorted to voltage for greater than 5 s.

### Action Taken When the DTC Sets

DTCs P0325 00, P0327 00, and P0328 00 are Type C DTCs.

### Conditions for Clearing the DTC

DTCs P0325 00, P0327 00, and P0328 00 are Type C DTCs.

### Diagnostic Aids

• | Inspect the knock sensor for physical damage and proper installation. A knock sensor that is dropped or damaged may cause a DTC to set.

• | Inspect the knock sensor for proper installation. A knock sensor that is loose or over torqued may cause a DTC to set. The knock sensor should be free of thread sealant.

• | The knock sensor mounting surface should be free of burrs, casting flash, and foreign material.

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Knock Sensor (KS) System Description

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Verification

1. Engine running, observe the DTC information with a scan tool. DTC P0325 00, P0327 00, or P0328 00 should not set.
2. Operate the vehicle within the conditions for running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the freeze frame / failure records data.

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the B68 Knock Sensor (KS).
2. Ignition ON, test for 1 to 2 V between the low reference circuit terminal 2 and ground.

⇒ | If less than the specified range, test the circuit for a short to ground or an open / high resistance. If the circuit tests normal, replace the K20 Engine Control Module (ECM).

⇒ | If greater than the specified range, test the low reference circuit for a short to voltage. If the circuit tests normal, replace the K20 Engine Control Module (ECM).

3. Ignition ON, test for 2.5 to 3.5 V between the signal circuit terminal 1 and ground.

⇒ | If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module (ECM).

⇒ | If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the K20 Engine Control Module (ECM).

4. If all circuits test normal, test or replace the B68 Knock Sensor (KS).

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Knock Sensor Replacement

• | Control Module References for ECM replacement, setup, and programming