P0325

DTC P0325

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions provide 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

Circuit/System Verification

1. Start the engine. Observe the DTC information with a scan tool. DTC P0325 should not set.
2. If the vehicle passes the Circuit/System Verification test, then operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records List.

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 signal circuit and ground.

• If less than the specified value, test the signal circuit for a short to ground or an open/high resistance. If the circuits/connections test normal, replace the ECM.
• If greater than the specified value, test the signal circuit for a short to voltage. If the circuits/connections test normal, replace the ECM.

3. Ignition ON, test for 2-3 volts between the low reference circuit and ground.

• If less than the specified value, test the low reference circuit for a short to ground or an open/high resistance. If the circuits/connections test normal, replace the ECM.
• If greater than the specified value, test the low reference circuit for a short to voltage. If the circuits/connections test normal, replace the ECM.

4. If all circuits/connections test normal, replace the KS sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests

* Knock Sensor Replacement
* Programming and Relearning for ECM setup, and programming Programming and Relearning