DTC P0325 or P0326 - Without FX3
Diagnostic Instructions
DTC Descriptor
DTC P0326: Knock Sensor Performance
Circuit/System Description
The knock sensor 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 knock sensor produces an AC voltage signal that varies depending on the vibration level during engine operation. The ECM adjusts the spark timing based on the amplitude and the frequency of the knock sensor signal. The ECM receives the knock sensor signal through a signal circuit and a low reference circuit. The ECM learns a minimum knock sensor noise level at idle and uses calibrated values for the rest of the RPM range. The ECM should monitor a normal knock sensor signal within the noise channel.
Conditions for Running the DTC
• | The engine coolant temperature is greater than 60°C (140°F). |
• | The mass air flow is greater than 170 mg/tdc |
• | The engine speed is greater than 2496 RPM. |
• | The DTC runs continuously when the above conditions are met. |
Conditions for Setting the DTC
The ECM detects that the measured knock sensor signal voltage is less than 0.3490 V for 10 s.
Action Taken When the DTC Sets
DTC P0326 is a Type C DTC.
Conditions for Clearing the DTC
DTC P0326 is a Type C DTC.
Diagnostic Aids
• | Inspect the knock sensor for physical damage and proper installation. A knock sensor that is dropped or damaged may cause a DTC to set. |
• | Loosen the mounting screw of the knock sensor and tighten the screw again using the specified torque. A knock sensor that is loose or over torqued may cause a DTC to set. |
• | Search the engine block and its environment for parts that vibrate but are not supposed to. Loose or faulty parts may cause high-frequency vibrations in the engine block which can disturb the knock sensor. |
Reference Information
Schematic Reference
Engine Controls Schematics : Siemens ECM - LPG with LCP → Siemens ECM - Gas without FX3 or LCP → Delphi ECM - FX3
Connector End View Reference
Component Connector End Views
Description and Operation
Knock Sensor 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 Testing
- Ignition OFF, disconnect the harness connectors at the K20 Engine Control Module and the B68 knock Sensor.
- Ignition ON, test for less than 0.3 V between the circuit terminal below and ground.
• | Signal circuit terminal 42 of the K20 ECM harness connector |
• | Low reference circuit terminal 12 of the K20 ECM harness connector |
⇒ | If greater than the specified range, test the circuit for a short to voltage. |
- Ignition OFF, test for greater than 500 kΩ between the circuit terminal below and ground.
• | Signal circuit terminal 42 of the K20 ECM harness connector. |
• | Low reference circuit terminal 12 of the K20 ECM harness connector |
⇒ | If less than the specified value, test the circuit for a short to ground. |
- If the circuits test normal, replace the B68 knock Sensor.
- Verify the DTC does not reset.
⇒ | If the DTC resets, replace the K20 engine Control Module. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
© Copyright Chevrolet. All rights reserved |