Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provide an overview of each diagnostic category. |
DTC Descriptors
DTC P0325: Knock Sensor (KS) CircuitDTC P0326: Knock Sensor (KS) Performance
Diagnostic Fault Information
Circuit | Short to Ground | High Resistance | Open | Short to Voltage | Signal Performance |
|---|---|---|---|---|---|
Knock Sensor Signal | P0325 | P0325 | P0325 | P0325 | P0326 |
Circuit/System Description
The knock sensor (KS) 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 KS is located on the intake side of the engine block. The KS produces an AC voltage signal that varies depending on the vibration level during engine operation. The ECM receives the KS signal through a signal circuit and a low reference circuit. The ECM adjusts the spark timing based on the amplitude and the frequency of the KS signal.
Conditions for Running the DTC
These DTCs run continuously when:
| • | DTCs P0335, P0336, P0340, P0341, P0365, P0366, P0601, P0602, or P0604 are not set. |
| • | The engine speed is greater than 2,500 RPM. |
| • | The mass air flow (MAF) is greater than 20 g/s. |
| • | The engine is NOT in decel fuel cut-off. |
Conditions for Setting the DTC
P0325
The KS signal voltage is above or below a calibrated range for 20 engine revolutions.
P0326
The KS signal is not present for 20 engine revolutions.
Action Taken When the DTC Sets
DTCs P0325 and P0326 are Type B DTCs.
Conditions for Clearing the MIL/DTC
DTCs P0325 and P0326 are Type B DTCs.
Diagnostic Aids
| • | 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. |
Reference Information
Schematic Reference
Connector End View Reference
Description and Operation
Knock Sensor (KS) System Description
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Testing
- Ignition ON, engine OFF.
- Disconnect the KS harness connector.
- Measure for 2-5 volts between the signal circuit terminal 1 and ground on the ECM side of the harness connector.
- Measure for less than 5 ohms between the low reference circuit terminal 2 and ground.
- If the circuits test normal, replace the KS.
| ⇒ | 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 ECM. |
| ⇒ | If greater than the specified range, test the circuits for a short to voltage. If the circuits test normal, replace the ECM. |
| ⇒ | If greater than the specified range, test the circuit for an open/high resistance. If the circuit tests normal, replace the ECM. |
Component Testing
- Connect the DMM between the KS signal circuit terminal 1 and the low reference circuit terminal 2 on the sensor side of the KS harness connector.
- Set the DMM to the 400 mV AC hertz scale and wait for the DMM to stabilize at 0 Hz.
- Tap on the engine block with a non-metallic object near the KS while observing the signal indicated on the DMM.
- The DMM should display a fluctuating frequency while tapping on the engine block.
Important: DO NOT tap on plastic engine components.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for ECM replacement, setup, and programming |
