GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2008 🢒 LaCrosse 🢒 Safety and Security 🢒 Supplemental Inflatable Restraints 🢒 DTC P0328 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 provides an overview of each diagnostic category.

DTC Descriptors

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

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

Circuit/System Description

The knock sensor (KS) is a piezoelectric device that produces an AC voltage of different amplitude and frequency depending on the level of engine mechanical vibration. The KS system monitors the knock sensor in order to determine if detonation or spark knock is present. If the KS system determines that excessive knock is present, the engine control module (ECM) retards the spark timing based on the signal from the KS system. The KS produces an AC signal when specific frequencies are detected. The ECM then retards the timing until knock is controlled.

In order to differentiate between normal engine noise and spark knock, the ECM samples the KS signal. The ECM samples the KS signal for a certain length of time under different engine speeds and loads during non-cylinder knock events. This sampling is used to determine a range of acceptable normal engine noise.

Conditions for Running the DTCs
    • Before the ECM can report DTC P0328, or P0333 failed, DTCs P0324, P0335, P0336, and P0338 must run and pass.
    • DTCs P0341, P0342, P0343, P0346, P0347, P0348, P0366, P0367, P0368, P0391, P0392, and P0393 are not set.
    • The ECM is controlling spark.
    • The engine coolant temperature (ECT) sensor is greater than 60°C (140°F).
    • The engine speed is greater than 2,000 RPM and steady.
    • The volumetric efficiency is steady.
    • The engine is not in reduced power mode.
    • DTCs P0327 and P0332 run continuously once the above conditions are met for approximately 20 seconds.

Conditions for Setting the DTCs

The ECM detects a KS signal voltage that is greater than the predetermined maximum engine noise level for greater than 4 seconds or for a cumulative of 50 seconds.

Action Taken When the DTC Sets

DTCs P0328, and P0333 are Type B DTCs.

Conditions for Clearing the DTC

DTCs P0328, and P0333 are Type B DTCs.

Diagnostic Aids

The following table illustrates the ECM connector locations:

ECM Connector Location

X2

X1

Front of Vehicle

    • 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.
    • The normal voltage on the KS signal and low reference circuits is 2.43 volts when the KS is disconnected.
    • A short to voltage on a signal or low reference circuit will cause a KS DTC to set for both banks of the engine.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Knock Sensor (KS) System Description

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 Verification
  1. Engine at operating temperature, all accessories OFF. Engine speed greater than 2,000 RPM, observe the appropriate KS signal voltage parameter with a scan tool. The voltage should be greater than 2 volts.
  2. Engine idling, move the related harnesses and connectors for the KS circuits while observing the KS signal voltage parameters with a scan tool. The voltage should remain steady with no abrupt changes.
  3. Operate the vehicle within the conditions for running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records Data List.

Circuit/System Testing
  1. Ignition OFF, disconnect the harness connector at the appropriate KS.
  2. Ignition ON, test for 2-3 volts between the signal circuit terminal 1 and ground.
    3. ⇒If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuits/connections test normal, replace the ECM.
    ⇒ If greater than the specified range, test the signal circuit for a short to voltage. If the circuits/connections test normal, replace the ECM.
  3. Test for 2-3 volts between the low reference circuit terminal 2 and ground.
    4. ⇒If less than the specified range, test the low reference circuit for a short to ground or an open/high resistance. If the circuits/connections test normal, replace the ECM.
    ⇒ If greater than the specified range, test the low reference circuit for a short to voltage. If the circuits/connections test normal, replace the ECM.
  4. If all circuits/connections test normal, test or replace the KS sensor.

Component Testing

Test for greater than 30 mV AC, while tapping on the engine block with a non-metallic object, near the KS.

⇒If less than the specified range, replace the KS.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Knock Sensor Replacement - Bank 1
    •  Knock Sensor Replacement - Bank 2
    •  Control Module References for engine control module replacement, setup, and programming