GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2006 🢒 STS 🢒 Vehicle Control Systems 🢒 Vehicle DTC Information 🢒 DTC P0324, P0325, P0326, P0327, P0328, P0330, P0331, P0332, or P0333

DTC Descriptors

DTC P0324: Knock Sensor (KS) Module Performance

DTC P0325: Knock Sensor (KS) Circuit Bank 1

DTC P0326: Knock Sensor (KS) Performance

DTC P0327: Knock Sensor (KS) Circuit Low Frequency Bank 1

DTC P0328: Knock Sensor (KS) Circuit High Frequency Bank 1

DTC P0330: Knock Sensor (KS) Circuit Bank 2

DTC P0332: Knock Sensor (KS) Circuit Low Frequency Bank 2

DTC P0333: Knock Sensor (KS) Circuit High Frequency Bank 2

Diagnostic Fault Information

Perform the prior to using this diagnostic procedure.

Circuit

Short to Ground

High Resistance

Open

Short to Voltage

Signal Performance

Knock Sensor Signal

P0327, P0328, P0332, P0333

P0325, P0330

P0325, P0330

P0327, P0328, P0332, P0333

P0326

Low Reference

P0327, P0328, P0332, P0333

P0325, P0330

P0325, P0330

P0327, P0328, P0332, P0333

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
    • DTCs P0324, P0325 and P0330 run continuously when the engine speed is greater than or equal to 2,000 RPM and engine load is greater than a calibrated amount.
    • DTCs P0326 run continuously when:
       - The engine speed is greater than or equal to 800 RPM
       - The MAP is greater than 42 kPa
       - DTCs P0120, P0121, P0122, or P0123 are not set
    • DTC P0325, P0330, P0327, P0328, P0332, P0333 run continuously when:
       - The engine speed is greater than or equal to 1,500 RPM
       - The engine coolant temperature (ECT) is greater than 75°C (167°F)
       - The engine run time is greater than 90 seconds

Conditions for Setting the DTC

P0324

The control module has detected an internal circuitry fault.

P0325 and P0330

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

P0326

    • The KS signal indicates an excessively noisy engine component (e.g. loose bracket, noisy lifter).
    • 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, P0328, P0332, and P0333

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.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

    •  Engine Control Module Connector End Views
    •  Engine Controls Connector End Views

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs
    •  Measuring Frequency

Scan Tool Reference

    •  Scan Tool Data List
    •  Scan Tool Data Definitions

Circuit/System Testing

P0324

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

P0325, P0327, P0328, P0330, P0332, and P0333

  1. Turn OFF the ignition.
  2. Disconnect the KS inline connector at the back of the engine.
  3. Measure for infinite resistance from the KS signal circuit on the sensor side of the KS harness connector to a good ground and from the KS low reference circuit on the sensor side of the KS harness connector to a good ground with the DMM.
    4. ⇒If either of the circuits are grounded, repair the short to ground.
  4. Measure for infinite resistance from the KS signal circuit on the ECM side of the KS harness connector to a good ground and from the KS low reference circuit on the ECM side of the KS harness connector to a good ground with the DMM.
    5. ⇒If either of 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 for less than 4.2 DC volts from the KS low reference circuit to a good ground with a DMM.
    7. ⇒If the KS low reference circuit measures more than 4.2 volts, inspect for a short to voltage. If the circuit tests normal, replace the control module.
  7. On the control module side of the KS harness connector, measure for less than 4.2 DC volts from the KS signal circuit to a good ground with a DMM.
    8. ⇒If the KS signal circuit measures more than 4.2 volts, inspect for a short to voltage. If the circuit tests normal, replace the control module.
  8. Test the KS signal circuit and the KS low reference circuit for the following conditions on the ECM side of the harness connector and on the sensor side of the harness connector:
    9. • An open
    • High resistance
    • Shorted to each other or any other circuit.
         ⇒If the circuits and the sensor test normal, replace the control module.

P0326

       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
  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. Important: DO NOT tap on plastic engine components.

  3. Tap on the engine block with a non-metallic object near the KS while observing the signal indicated on the DMM.
  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 2 Replacement
    •  Control Module References for ECM replacement, setup, and programming
    •  Symptoms - Engine Mechanical
    •  Symptoms - Engine Controls