DTC Descriptor
DTC P0326: Knock Sensor (KS) PerformanceDiagnostic Fault Information
Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
Circuit | Short to Ground | High Resistance | Open | Short to Voltage | Signal Performance |
|---|---|---|---|---|---|
Knock Sensor Signal | P0327, P0332 | P0325 | P0325 | P0327, P0332 | P0326 |
Low Reference | P0327, P0332 | P0325 | P0325 | P0327, P0332 | P0326 |
Circuit/System Description
The knock sensor (KS) system enables the control module 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 control module adjusts the spark timing based on the amplitude and the frequency of the KS signal. The control module receives the KS signal through 2 isolated signal circuits. The control module learns a minimum KS noise level at idle and uses calibrated values for the rest of the RPM range. The control module should monitor a normal KS signal within the noise channel.
Conditions for Running the DTC
| • | The engine speed is greater than or equal to 1,800 RPM. |
| • | The MAP is greater than 55 kPa. |
| • | DTCs P0120, P0121, P0122, or P0123 are not set. |
Conditions for Setting the DTC
P0326
| • | The KS signal indicates an excessive engine knock is present. |
| • | The control module commanded spark retard at a given engine load and speed is more than the calibrated value. |
| • | The above conditions exist for 6 seconds. |
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. |
| • | The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
| • | A current DTC, Last Test Failed, clears when the diagnostic runs and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
| • | Clear the MIL and the DTC with a scan tool. |
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. |
| • | The KS must be clear of hoses, brackets, and engine electrical wiring. |
Reference Information
Schematic Reference
Connector End View Reference
Electrical Information Reference
Scan Tool Reference
Circuit/System Testing
| Important: If DTC P0335 or P0336 are also set, diagnose those DTCs first. |
| • | Inspect for a loose or broken vehicle accessory or accessory bracket. |
| • | Inspect for excessive engine mechanical noise. |
Component Testing
- Connect the DMM from the KS signal circuit to the KS low reference circuit 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 |
