P0325
DTC P0325, P0327, or P0328
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 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 2 isolated signal circuits. The ECM learns a minimum knock sensor noise level for all of the RPM range. The ECM monitors for a normal knock sensor signal. The ECM generates a 20 KHz signal on the output circuit and monitors that it is sent back and detected on the return circuit. The ECM processes the return signal to verify the internal knock sensor processor.
Conditions for Running the DTCs
P0325
* Engine speed is between 400-8,500 RPM.
* Engine is running at least 2 s.
* The engine coolant temperature (ECT) is warmer than -40°C (-40°F).
* The intake air temperature (IAT) is warmer than -40°C (-40°F).
* The DTC runs continuously when the above conditions are met.
P0327 and P0328
* Engine speed is less than 8,500 RPM.
* The DTCs run continuously when the above condition is met.
Conditions for Setting the DTCs
P0325
The knock sensor signal circuits are open for least 6 s.
P0327
The knock sensor signal circuits are shorted to ground for least 6 s.
P0328
The knock sensor signal circuits are shorted to voltage for least 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
* 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 (LUK) [1][2]Electrical Diagrams
Connector End View Reference
Component Connector End Views Sunshade - Left
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.
2. Verify DTC P0325, P0327, P0328, P0330, P0332, or P0333 is not set.
• If the DTC is set
Refer to Circuit/System Testing.
• If the DTC is not set
3. Verify the appropriate B68 Knock Sensor is properly tightened. Refer to Fastener Tightening Specifications Specifications.
4. Verify the scan tool parameters below display NO while moving the related harnesses and connectors for the appropriate B68 Knock Sensor.
* Cylinder 1 Knock Detected
* Cylinder 2 Knock Detected
* Cylinder 3 Knock Detected
* Cylinder 4 Knock Detected
• If NO is not displayed
Refer to Circuit/System Testing.
• 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.
• If the DTC is set
Refer to Circuit/System Testing.
• If the DTC is not set
6. All OK.
Circuit/System Testing
1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the appropriate B68 Knock Sensor. It may take up to 2 min for all vehicle systems to power down.
2. Test for less than 10 ohms between the low reference circuit terminal B or 2 and ground.
• If 10 ohms or greater
1. Ignition OFF, disconnect the X2 harness connector at the K20 Engine Control Module.
2. Test for less than 2 ohms in the low reference 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 less than 10 ohms
3. Test for 1-4 V between the signal circuit terminal A or 1 and ground.
• If greater than 4 V
1. Ignition OFF, disconnect the X2 harness connector at the K20 Engine Control Module, ignition ON.
2. Test for less than 1 V between the 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.
4. If less than 1 V
1. Ignition OFF, disconnect the X2 harness connector at the K20 Engine Control Module.
2. Test for infinite resistance between the signal circuit 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 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 between 1-4 V
5. 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 engine control module replacement, programming, and setup.