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 1 Circuit
DTC P0326 00: Knock Sensor Performance

### Diagnostic Fault Information

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

Component | Condition | DTCs
--- | --- | ---
Knock Sensor |

• | Improper installation

• | Loose or faulty parts may cause high-frequency vibrations in the engine block which can disturb the knock sensor. Search the engine block and its environment for parts that vibrate but are not supposed to.

P0325 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 A/C 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

• | The engine is running.

• | The engine speed is greater than 2500 RPM.

• | DTC P0340 00, P0341 00, P0365 00, P0366 00, P0335 00, P0336 00, P0601 00, P0602 00 or P0604 00 are not set.

• | This DTC runs continuously within the enabling conditions.

### Conditions for Setting the DTC

The knock signal is checked continuously by a range check of the signal and with two algorithms, which observe the signal bandwidth.

### Action Taken When the DTC Sets

DTCs P0325 00, P0326 00 are Type B DTCs.

### Conditions for Clearing the DTC

DTCs P0325 00, P0326 00 are Type B 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.

• | Loosen the mounting screw of the knock sensor and tighten the screw again using the specified torque. A knock sensor that is loose or over torqued may cause a DTC to set.

• | Search the engine block and it's environment for parts that vibrate but are not supposed to. Loose or faulty parts may cause high-frequency vibrations in the engine block which can disturb the knock sensor.

### 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 Testing

1. Ignition ON, engine OFF.
2. Disconnect the B68 Knock Sensor (KS) harness connector.
3. Measure for 2-5 V between the signal circuit terminal 1 and ground on the K20 Engine Control Module (ECM) side of the harness connector.

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

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

4. Measure for less than 5 Ω between the low reference circuit terminal 2 and ground.

⇒ | If greater than the specified range, test the circuit for an open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module (ECM).

5. If the circuits test normal, replace the B68 Knock Sensor (KS).

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Knock Sensor Replacement

• | Symptoms - Engine Controls

• | Symptoms - Engine Mechanical

• | Engine Control Module Replacement for ECM replacement, setup, and programming