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.
2003 Hummer H2FACTORY OEM SERVICE PROCEDURE
Section 38 (Engine Control System - Self-Diagnostics)
WARNING: This page is about a different car, the 2003 Pontiac Vibe. However, it is still accessible from the selected car via links, so may be relevant.
- Introduction
- Self-Diagnostic System
- Programming
- Drive Cycles
- Notes
- Inspection/Maintenance System Check
- Inspection/Maintenance Complete System Set Procedure
- Inspection/Maintenance System DTCS
- Inspection/Maintenance Catalyst System Set Procedure
- Inspection/Maintenance EVAP System Set Procedure
- Inspection/Maintenance Heated Oxygen Sensor/Oxygen Sensor (Ho2S/O2S) System Set Procedure
- Inspection/Maintenance (I/M) Heated Oxygen Sensor (Ho2S) Heater System Set Procedure
- Summary
- Diagnostic Trouble Code Definitions
- Component Locations
- Connector Identification
- System Tests
- Diagnostic Tests
- Notes
- DTC P0100: MAF Sensor Circuit
- DTC P0101: MAF Sensor Performance
- DTC P0110: IAT Sensor Circuit
- DTC P0115: ECT Sensor Circuit
- DTC P0116: ECT Sensor Circuit Performance
- DTC P0120: TP Sensor Circuit
- DTC P0121: TP Sensor Performance
- DTC P0125: ECT Excessive Time To Enter Closed Loop
- DTC P0128: ECT Below Thermostat Regulating Temperature
- DTC P0130: Ho2S 1 Circuit
- DTC P0133: Ho2S 1 Slow Response
- DTC P0135 Or P0141: Ho2S 1 Or 2 Heater Performance
- DTC P0136: Ho2S 2 Circuit
- DTC P0138: Ho2S Circuit - High Voltage
- DTC P0140: Ho2S 2 Circuit Insufficient Activity (Bank 1)
- DTC P0141: Ho2S 2 Heater Performance (Bank 1)
- DTC P0171: Fuel Trim System Lean
- DTC P0172: Fuel Trim System Rich
- DTC P0300: Engine Misfire Detected
- DTC P0301, P0302, P0303, P0304: Cylinder Specific Misfire Detected
- DTC P0325: Knock Sensor Module Circuit
- DTC P0335: CKP Sensor Circuit
- DTC P0340: CMP Sensor Circuit
- DTC P0420: Catalyst System Low Efficiency
- DTC P0440: EVAP System
- DTC P0441: EVAP System No Flow During Purge
- DTC P0442: EVAP System - Small Leak Detected
- DTC P0443: EVAP Purge Solenoid Control Circuit
- DTC P0446: EVAP Vent System Performance
- DTC P0450: Fuel Tank Pressure Sensor Circuit
- DTC P0451: Fuel Tank Pressure Sensor Performance
- DTC P0500: VSS Circuit
- DTC P0505: Idle Control System
- DTC P0601, P0602, P0603, P0604, P0605, P0606, P0607, P1600, P1621, P1627, P1680, P1681, P1683 Or P2610: Ecu Malfunction
- DTC P0710: TFT Sensor Circuit
- DTC P1300, P1305, P1310, P1315: Ignition Coil Primary Feedback Circuits
- DTC P1335: CKP Sensor Circuit
- DTC P1346: Intake CMP System Performance
- DTC P1349: Intake CMP System Performance
- DTC P1656: Intake Camshaft Position Actuator Solenoid Control Circuit
- DTC P1690: Rocker Arm Actuator Solenoid Control Circuit
- DTC P1692: Rocker Arm Actuator System Stuck On
- DTC P1693: Rocker Arm Actuator System Stuck Off
Factory Service Tools
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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.
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