Chevrolet Trax: DTC P0325, P0327, OR P0328

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 Descriptors

DTC P0325

Knock Sensor Circuit

DTC P0327

Knock Sensor Circuit Low Voltage

DTC P0328

Knock Sensor Circuit High Voltage

Diagnostic Fault Information

Circuit/System Description

The knock sensor 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 alternating current (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 learns a minimum knock sensor noise level for all of the engine speed ranges and monitors the normal knock sensor signal. The ECM monitors the internal knock sensor processor test circuits which perform the open circuit diagnostic.

Conditions for Running the DTCs

P0325

• Engine is running for 2 s or greater.
• Engine speed is between 500-7000 RPM for 67 or more cumulative revolutions.
• The engine coolant temperature (ECT) is -40ºC (-40ºF) or warmer.
• The intake air temperature (IAT) sensor is -40ºC (-40ºF) or warmer.

P0327 or P0328

Engine speed is less than 8,500 RPM.

The DTCs run continuously when the above conditions are met.

Conditions for Setting the DTCs

P0325

The ECM detects that a knock sensor signal circuit is open for greater than 6 s.

P0327

The ECM detects that a knock sensor signal circuit is shorted to ground for greater than 6 s.

P0328

The ECM detects that a knock sensor signal circuit is shorted to voltage for greater than 6 s.

Action Taken When the DTCs Set

DTCs P0325, P0327 and P0328 are Type B DTCs.

The ignition timing is retarded to reduce the potential of engine damaging spark knock.

Conditions for Clearing the DTCs

DTCs P0325, P0327 and P0328 are Type B DTCs.

Diagnostic Aids

The following conditions listed below may cause a knock sensor DTC to set:

• Sensor damage.
• Knock sensor and engine mounting surface burrs, casting flash, and foreign material.
• Close proximity of hoses, brackets, and engine wiring.
• Loose brackets.
• Loose or broken accessory drive belts, brackets, components.
• An engine mechanical condition. Refer to Symptoms - Engine Mechanical .

Reference Information

Schematic Reference

Engine Controls Schematics (Encore) , Engine Controls Schematics (Trax)

Connector End View Reference

WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - ENCORE WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - TRAX

Description and Operation

Electronic Ignition System Descri

Electrical Information Reference

Testing for Intermittent Conditions and Poor Connections Circuit Testing Wiring Repairs Connector Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions (LUV) , Powertrain Diagnostic Trouble Code (DTC) Type Definitions (2H0)

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Engine Running
2. Verify DTC P0325, P0327 or P0328 is not set.

• If the DTC is set

Refer to Circuit/System Testing.

• If the DTC is not set

3. Verify the B68 Knock Sensor mounting bolt is properly tightened. Refer to Fastener Tightening Specifications

• If not tightened to the correct specification

Repair a necessary.

• If tightened to the correct specification

4. Verify the scan tool parameters listed below display No while moving the related harnesses and connectors of the B68 Knock Sensor.

• Cylinder 1 Knock Detected
• Cylinder 2 Knock Detected
• Cylinder 3 Knock Detected
• Cylinder 4 Knock Detected
• If No is not displayed

Repair the wiring harness or connectors.

• If No is displayed

5. Operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
6. Verify the DTC does not set.

• If the DTC sets

Refer to Circuit/System Testing.

• If the DTC does not set

7. All OK.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the B68 Knock Sensor, ignition ON.
2. Test for 1-2 V between the low signal circuit terminal 2 and ground.

• If less than 1 V

1. Ignition OFF, disconnect the harness connector at the K20 Engine Control Module.
2. Test for infinite resistance between the low signal circuit terminal 2 and ground.

• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance

3. Test for less than 2 ohms in the low signal circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K20 Engine Control Module.
• If greater than 2 V

1. Ignition OFF, disconnect the harness connector at the K20 Engine Control Module, ignition ON.
2. Test for less than 1 V between the low signal circuit and ground.

• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, replace the K20 Engine Control Module.
• If between 1-2 V

3. Test for 2-4 V between the high signal circuit terminal 1 and ground.

• If less than 2 V

1. Ignition OFF, disconnect the harness connector at the K20 Engine Control Module.
2. Test for infinite resistance between the high signal circuit terminal 1 and ground.

• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance.

3. Test for less than 2 ohms in the high signal circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K20 Engine Control Module.

  If greater than 4 V

1. Ignition OFF, disconnect the harness connector at the K20 Engine Control Module, ignition ON.
2. Test for less than 1 V between the high signal circuit and ground.

• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, replace the K20 Engine Control Module.
• If between 2-4 V

4. Test or replace the B68 Knock Sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

• Knock Sensor Replacement
• Control Module References for engine control module replacement, programming, and setup.

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