Diagnostic Instructions
DTC Descriptors
DTC P0326: Knock Sensor (KS) System Performance 1
DTC P0327: Knock Sensor (KS) Circuit Low Voltage Bank 1
DTC P0328: Knock Sensor (KS) Circuit High Voltage Bank 1
DTC P0331: Knock Sensor (KS) System Performance Bank 2
DTC P0332: Knock Sensor (KS) Circuit Low Voltage Bank 2
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
P0326 and P0331
| • | Before the ECM can report DTC P0326 or P0331 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 engine coolant temperature (ECT) sensor is greater than 60°C (140°F). |
| • | The engine speed is greater than 2,200 RPM. |
| • | DTCs P0326 and P0331 run continuously once the above conditions are met for approximately 20 seconds. |
P0327, P0328, P0332, and P0333
| • | Before the ECM can report DTC P0327 P0328, P0332, 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 engine coolant temperature (ECT) sensor is greater than 60°C (140°F). |
| • | The increase in engine speed is less than a range of 1500-2500 RPM per second. |
| • | The increase in engine load is less than a range of 50-100 kPa per second. |
| • | DTCs P0327, P0328, P0332, and P0332 run continuously once the above conditions are met for approximately 20 seconds. |
Conditions for Setting the DTCs
P0326 and P0331
The ECM detects a KS signal voltage that is not in the range of a predetermined engine noise level in 25 of 250 test samples. The condition exists for greater than 4 seconds or for a cumulative of 50 seconds.
P0327 or P0332
The ECM detects a KS signal voltage that is less than the typical engine noise level for at least 4 seconds or for a cumulative of 50 seconds.
P0328 or P0333
The ECM detects the KS signal voltage is greater than predetermined maximum engine noise level for greater than 4 seconds or for a cumulative of 50 seconds.
Action Taken When the DTC Sets
DTCs P0326, P0327, P0328, P0331, P0332, and P0333 are Type B DTCs.
Conditions for Clearing the DTC
DTCs P0326, P0327, P0328, P0331, P0332, and P0333 are Type B DTCs.
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. |
| • | 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
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References
for scan tool information
Circuit/System Verification
- Engine idling at operating temperature, all accessories OFF. Raise the engine speed greater than 2000 RPM, observe the appropriate scan tool KS signal voltage parameter. The voltage should be greater than 2 volts.
- Engine idling, move the related harnesses and connectors for the KS circuits while observing the scan tool KS signal voltage parameters. The voltage should remain steady with no abrupt changes.
- 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
- Ignition OFF, disconnect the harness connector at the appropriate KS.
Important: If the voltage is not within the specified range on either circuit, test for a short to ground or voltage between the KS circuits.
- Ignition ON, test for 2-3 volts between the low reference circuit terminal 2 and ground.
| ⇒ | 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. |
- Test for 2-3 volts between the signal circuit terminal 1 and ground.
| ⇒ | 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. |
- If all circuits/connections test normal, test or replace the KS sensor.
Component Testing
- Connect a DMM set to the AC mV scale, between the terminals of the KS.
- Tap on the engine block with a non-metallic object near the KS while observing the DMM.
- The DMM should display a fluctuating AC voltage greater than 30 mV while tapping on the engine block.
| ⇒ | If less than the specified valve, replace the KS. |
Repair Instructions
Perform the
Diagnostic Repair Verification
after completing the diagnostic procedure.
