P0325
DTC P0325
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview)provides an overview of each diagnostic category.
DTC Descriptor
DTC P0325
- Knock Sensor (KS) Circuit
Circuit/System Description
The knock sensor (KS) 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 KS 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 KS signal. The ECM receives the KS signal through a signal circuit. The ECM supples a ground circuit to the KS through a low reference circuit. The ECM also supplies a shielded ground circuit to the KS. The ECM learns a KS noise level at idle and uses calibrated values for the rest of the engine speed range. The ECM should monitor a normal KS signal within the noise channel. The circuits between the KS sensor and the ECM consist of the following circuits:
* A KS signal
* A low reference
* A shielded ground
Conditions for Running the DTC
* DTCs P0106, P0107, and P0108 are not set.
* The engine coolant temperature (ECT) is greater than 50°C (122°F).
* The engine speed is greater than 1,600 RPM.
* The manifold absolute pressure (MAP) is between 10-50 kPa which depends on engine speed.
* DTC P0325 runs continuously once the above conditions are met.
Conditions for Setting the DTC
The ECM detects an incorrect KS signal for greater than 4 seconds.
Action Taken When the DTC Sets
DTC P0325 is a Type B DTC.
Conditions for Clearing the DTC
DTC P0325 is a Type B DTC.
Diagnostic Aids
The following conditions could also set this DTC:
* Inspect the KS for physical damage. A KS that is dropped or damaged may cause a DTC to set.
* Inspect the KS for proper installation. A KS that is loose or over torqued may cause a DTC to set. The KS should be free of thread sealant. The KS mounting surface should be free of burrs, casting flash, and foreign material.
* The KS must be clear of hoses, brackets, and engine electrical wiring.
* An electromagnetic interference (EMI) condition on the shielded ground circuit
Reference Information
Schematic Reference
Engine Controls Schematics (MR140 w/o Throttle Actuator Control) (Electrical Diagrams)Engine Controls Schematics (MT34 w/Throttle Actuator Control) (Electrical Diagrams)Engine Controls Schematics (Hatchback) (Electrical Diagrams)
Description and Operation
Knock Sensor (KS) System Description (Knock Sensor (KS) System Description)
Electrical Information Reference
* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Diagnostic Trouble Code Descriptions)
Scan Tool Reference
Control Module References (Programming and Relearning)for scan tool information
Circuit/System Verification
1. Engine running, observe the DTC information with a scan tool. DTC P0325 should not set.
2. 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
Important: If the KS lead is damaged in any way, replace the KS.
1. Ignition OFF, disconnect the harness connector at the KS.
2. Ignition ON, test for 2-3 volts between the low reference circuit terminal 2 and ground.
• If less than the specified range, test the low reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
• If greater than the specified range, test the low reference circuit for a short to voltage. If the circuit tests normal, replace the ECM.
3. Ignition ON, test for 2-3 volts 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 ECM.
• If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.
4. If all circuits test normal, test or replace the KS sensor.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Knock Sensor Replacement (Service and Repair)
* Control Module References (Programming and Relearning)for ECM replacement, setup, and programming