GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2008 🢒 Express 🢒 DTC 🢒 DTC P0324, P0325, P0326, P0327, P0328, P0330, P0332, or P0333

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 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

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Knock Sensor Signal

P0327, P0328, P0332, P0333

P0325, P0330

P0327, P0332

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 ECM monitors 2 separate KS, one on each side of the engine block. Each KS produces an AC voltage that varies, depending on the vibration levels detected during engine operation. The ECM receives the KS signal through 2 isolated signal circuits for each KS. The ECM adjusts the spark timing based on the amplitude and frequency of each KS signal. The ECM learns a minimum noise level for each sensor at idle speeds, and uses calibrated noise level value for the rest of the RPM range. The ECM should monitor a normal KS signal within the noise channel.

Conditions for Running the DTC

P0324

This DTC runs continuously when the engine speed is greater than or equal to 1,500 RPM and the engine load is greater than a calibrated amount.

P0326

This DTC runs continuously when:

    • The engine speed is greater than or equal to 500 RPM.
    • The MAP is greater than 55 kPa.
    • DTCs P0120, P0121, P0122, or P0123 are not set.

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

The DTCs run continuously when:

    • The engine coolant temperature (ECT) is greater than 40°C (40°F).
    • The engine run time is greater than 1 second.
    • PTO is not active.

Conditions for Setting the DTC

P0324

The ECM has detected an internal circuitry fault.

P0325 or P0330

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

P0326

    • The KS signal indicates an engine knock is present.
    • The ECM has commanded the spark retard to a value which is more than the calibrated valve, for a specific engine load and speed.
    • The above conditions exist for more than 5 seconds.

P0327, P0328, P0332, and P0333

The KS signal circuits are shorted to voltage or ground.

Action Taken When the DTC Sets

DTCs P0324, P0325, P0326, P0327, P0328, P0330, P0332, and P0333 are Type B codes.

Conditions for Clearing the DTC

DTCs P0324, P0325, P0326, P0327, P0328, P0330, P0332, and P0333 are Type B codes.

Diagnostic Aids
    • Inspect the KS for physical damage. A KS that is drop or damage 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 mounting surface should be free of burs, casting flash, and foreign material.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

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

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Testing

P0324

Important: If DTCs P0325, P0327, P0328, P0330, P0332, or P0333 are also set, diagnose those DTCs first.

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

P0325, P0327, P0328, P0330, P0332, or P0333

  1. Ignition ON, engine OFF.
  2. Disconnect the appropriate KS harness connector.
  3. Measure for 2-3 volts between each of the following circuits and ground on the ECM side of the harness connector.
    4. • The KS signal circuit terminal A
    • The KS low reference circuit terminal B
         ⇒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.
  4. If all circuits test normal, replace the KS.

P0326

       Important: If DTC P0325, P0327, P0328, P0330, or P0333 are also set, diagnose those DTCs first.

    • Inspect for a loose or broken engine mount, engine mounted accessory, or accessory mounting bracket.
    • Inspect for excessive engine mechanical noise. Refer to Symptoms - Engine Mechanical.

Component Testing
  1. Connect a DMM to the KS signal circuit and to the KS low reference circuit at the KS.
  2. Set the DMM to the 400 mv AC hertz scale and wait for the DMM display 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

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Engine Control Module Programming and Setup
    •  Engine Control Module Replacement
    •  Knock Sensor 1 Replacement
    •  Knock Sensor 2 Replacement