P0325
DTC P0325, P0327, or P0328 (LUW)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions 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 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 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 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
* Engine speed is between 600-8 500 RPM.
* The ECT is greater than -40°C (-40°F).
* The IAT is greater than -40°C (-40°F).
* The engine runtime is greater than 5 s.
* The DTC runs continuously when the above conditions are met.
P0327 or P0328
* Engine speed is between 0-8 500 RPM.
* DTCs P0327 and P0328 run continuously when the above condition is met.
Conditions for Setting the DTC
P0325
The ECM detects the knock sensor signal circuit is open for greater than 5 s.
P0327
The ECM detects that the sensor input signal is less than 0.57 V or the sensor return signal is less than 0.40 V for greater than 5 s.
P0328
The ECM detects that the sensor input signal is greater than 2.76 V or the sensor return signal is greater than 1.95 V for greater than 5 s.
Action Taken When the DTC Sets
* 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 DTC
DTCs P0325, P0327, and P0328 are Type B DTCs.
Diagnostic Aids
* Inspect the knock sensor for physical damage. 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 [1][2]Electrical Diagrams
Connector End View Reference
Component Connector End Views Fuel Pump and Level Sensor Assembly
Description and Operation
Electronic Ignition System Description Description and Operation
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References Control Module References for scan tool information
Circuit/System Verification
1. Engine running, observe the DTC information with a scan tool. Verify DTC P0325, P0327, P0328 or P06B6 are not set.
• If DTC P0325, P0327, or P0328 is set with P06B6 continue with Circuit/System Testing.
• If only DTC P06B6 is set, and no external knock sensor circuit issues exist, replace the K20 Engine Control Module.
2. Move the related harnesses and connectors for the affected knock sensor circuits while observing the scan tool parameters listed below. The parameters should display NO.
* Cylinder 1 Knock Detected
* Cylinder 2 Knock Detected
* Cylinder 3 Knock Detected
* Cylinder 4 Knock Detected
• If the parameters change, repair the wiring or the harness connectors.
3. Observe the DTC information with a scan tool. DTC P0325, P0327, or P0328 should not set.
4. 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.
2. Ignition ON, test for 1-2 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.
• 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.
3. Ignition ON, test for 2.5-3.5 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.
• 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.
4. If all circuits test normal, test or replace the B68 Knock Sensor.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Knock Sensor Replacement Service and Repair
* Control Module References Control Module References for ECM replacement, programming, and setup.