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.
SYS.OK|MANUAL.DB● LIVE
HOMESERVICE MANUALSCHEVROLET2003TRAILBLAZER 4.2 S, 4WDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 380 (ENGINE CONTROLS SELF-DIAGNOSTICS - 3.1L ENGINE)DRIVE CYCLESINSPECTION/MAINTENANCE HEATED OXYGEN SENSOR HEATER SYSTEM SET PROCEDUREDIAGNOSTIC PROCEDURE
2003 Chevrolet TrailBlazer 4.2 S, 4WD
Diagnostic Procedure
2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Diagnostic Procedure
WARNING: This page is about a different car, the 2003 Pontiac Grand Prix, 2003 Chevrolet Malibu, and 2003 Buick Century. However, it is still accessible from the selected car via links, so may be relevant.
- Perform I/M system check. See INSPECTION/MAINTENANCE SYSTEM CHECK . After performing I/M system check, go to next step.
- Pre-program scan tool with vehicle information before ignition switch is turned to RUN position. Ensure vehicle is within enable criteria. Set vehicle parking brake. Verify transmission is in Park for A/T and Neutral for M/T. Turn OFF all accessories. Start the engine and allow it to idle for 2 minutes or until I/M SYSTEM STATUS indicator updates to YES. If HO2S HEATER SYSTEM STATUS updates to YES, go to step 5. If HO2S HEATER SYSTEM STATUS does not update to YES, go to next step.
- Using scan tool, observe DTC information. If scan tool indicates any failed DTCs, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If scan tool does not indicate any failed DTCs, go to next step.
- Determine which DTCs are required to run to complete this test. See INSPECTION/MAINTENANCE SYSTEM DTCS . Using scan tool, observe the NOT RAN SINCE CODE CLEARED display. Determine which of the DTCs required for a YES status has not run. Enter the DTC number in the SPECIFIC DTC menu of the scan tool. Operate vehicle within the Conditions for Running Test. See CONDITIONS FOR RUNNING TEST . Repeat the procedure until the scan tool indicates the diagnostic test has run. Repeat this procedure for any additional required DTCs that have not run. Using scan tool, observe the I/M System Status display. Did the HO2S Heater System Status update to YES? If yes, go to next step. If no, see DIAGNOSTIC AIDS .
- Using scan tool, check for DTCs. If scan tool indicates any DTCs are set, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no DTCs are set, system is okay at this time.
NOTE:
Whenever ignition switch is turned to RUN position, ignition voltage is supplied to HO2S heaters. After verifying enable criteria, turn ignition switch to OFF position for approximately 5 minutes to allow sensors to cool before continuing with test.
RENDER: 1.0x
NO RELATED
Recommended Tools & Savings
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Affiliate disclosure: We may earn a commission at no extra cost to you.
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.