Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSCHEVROLET2003TRAILBLAZER 4.2 S, 4WDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 89 (ENGINE CONTROL SYSTEM SELF-DIAGNOSTICS - 3.1L ENGINE)DIAGNOSTIC TESTSDTC P0325: KNOCK SENSOR MODULE CIRCUITDIAGNOSTIC PROCEDURES
2003 Chevrolet TrailBlazer 4.2 S, 4WD
Diagnostic Procedures
2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Diagnostic Procedures
WARNING: This page is about a different car, the 2002 Pontiac Grand Prix, 2002 Chevrolet Malibu, and 2002 Buick Century. However, it is still accessible from the selected car via links, so may be relevant.
- Perform diagnostic system check - engine controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM. After performing diagnostic system check - engine controls, go to next step.
- Observe the Freeze Frame/Failure Records data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate the vehicle within the Conditions for Running the DTC or within the observed parameters of the Freeze Frame/Failure Records. See CONDITIONS FOR RUNNING DTC . Does the DTC fail this ignition? If yes, go to next step. If no, see INTERMITTENT CONDITIONS under SELF-DIAGNOSTIC SYSTEM.
- Replace PCM. Perform PCM relearn procedure. See POWERTRAIN CONTROL MODULE under PROGRAMMING. After replacing PCM, go to next step.
- Use the scan tool in order to clear the DTCs. Turn ignition off for 30 seconds. Start engine. Operate the vehicle within the Conditions for Running in the DTC. See CONDITIONS FOR RUNNING DTC . Did the DTC Run and Pass? If yes, go to next step. If no, go to step 2.
- Using scan tool, observe stored information and Capture Info. Does scan tool displays any undiagnosed DTCs? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.