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Home >> Chevrolet >> 2006 >> Cobalt L4-2.4L VIN B >> Repair and Diagnosis >> A L L Diagnostic Trouble Codes ( DTC ) >> Testing and Inspection >> P Code Charts >> P0327

P0327



DTC P0327

DTC DESCRIPTORS

DTC P0324
Knock Sensor (KS) Module Performance

DTC P0325
Knock Sensor (KS) Circuit

DTC P0326
Knock Sensor (KS) Performance

DTC P0327
Knock Sensor (KS) Circuit Low Frequency

DTC P0328
Knock Sensor (KS) Circuit High Frequency

DIAGNOSTIC FAULT INFORMATION

IMPORTANT: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Testing and Inspection






TYPICAL SCAN TOOL DATA

Spark:






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 a signal circuit. The KS ground is supplied by the control module through a low reference circuit. 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
- DTCs P0325 and P0326 run continuously when the engine speed is greater than 1,800 RPM and manifold absolute pressure (MAP) is greater than 55 kPa.
- DTCs P0324, P0327, and P0328 run continuously when the ignition is ON or the engine is running.

CONDITIONS FOR SETTING THE DTC

P0324
The control module has detected an internal circuitry fault.

P0325
The KS signal circuits are open or shorted together for 5 seconds.

P0326
- The KS signal indicates an 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 5 seconds.

P0327 and P0328
The KS signal circuits are shorted to ground or power.

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.

CIRCUIT/SYSTEM TESTING

P0324
This DTC indicates an internal control module circuitry failure. Replace the ECM.

P0325, P0327, and P0328
1. Turn OFF the ignition.
2. Disconnect the KS.
3. Measure for infinite resistance from the KS signal circuit on the sensor side of the KS harness connector to a good ground with the DMM.
4. Measure for infinite resistance from the KS low reference circuit on the sensor side of the KS harness connector to a good ground with the DMM.
- If the circuits are grounded, repair the short to ground.
5. Turn ON the ignition, with the engine OFF.
6. On the control module side of the KS harness connector, measure the DC voltage from the KS signal circuit to a good ground with a DMM.
7. On the control module side of the KS harness connector, measure for less than 4.2 DC volts from the KS low reference circuit to a good ground with a DMM.
- If the KS signal circuit or the KS low reference circuit measures more than 4.2 volts, inspect for a short to voltage or a faulty controller.
8. Test the KS signal circuit and the KS low reference circuit for the following conditions:
- An open
- A short to ground
- High resistance
- If the circuits and the sensor test normal, replace the control module.

P0326
- Inspect for a loose or broken vehicle accessory or accessory bracket.
- Inspect for excessive engine mechanical noise.

COMPONENT TESTING
1. Connect the DMM from the KS signal circuit to the KS low reference circuit on the sensor side of the KS harness connector.
2. Set the DMM to the 400 mV AC hertz scale and wait for the DMM to stabilize at 0 Hz.
3. Tap on the engine block with a non-metallic object near the KS while observing the signal indicated on the DMM.

IMPORTANT: DO NOT tap on plastic engine components.

4. The DMM should display a fluctuating frequency while tapping on the engine block.

REPAIR INSTRUCTIONS

IMPORTANT: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure.
- Knock Sensor (KS) Replacement
- Control Module References for ECM replacement, setup, and programming
- Symptoms - Engine
- Symptoms - Computers and Control Systems
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