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 (KS) Circuit
DTC P0327
- Knock Sensor (KS) Circuit Low Voltage
DTC P0328
- Knock Sensor (KS) 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 (LE9) [1][2]Electrical Diagrams
Connector End View Reference
Component Connector End Views Sunshade - Left (DH6)
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, and 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. Verify the B68 knock sensor is properly tightened, refer to Fastener Tightening Specifications Specifications.
• If not the specified value, correct the condition as appropriate.
2. Ignition OFF, disconnect the harness connector at the B68 knock sensor.
3. Ignition ON, measure for 1-4 V between each of the following circuits and ground on the K20 engine control module side of the harness connector:
* The signal circuit, terminal A or 1
* The low reference circuit, terminal B or 2
• 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.
• 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.
4. If all circuits test normal, 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.