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 MANUALSCHEVROLET2008CHEVY EXPRESS G2500, VAN CARGO, 6.6 6REPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 1898 (ENGINE CONTROL SYSTEM & FUEL SYSTEM - 6.6L LMM - DTC P02E7 TO DTC P0700)DTC P0420CIRCUIT/SYSTEM TESTING
2008 Chevrolet Chevy Express G2500, Van Cargo, 6.6 6
Circuit/System Testing
2008 Chevrolet Chevy Express G2500, Van Cargo, 6.6 6SECTION Circuit/System Testing
WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2009 GMC Savana Special, 2009 GMC Savana Camper Special, 2009 GMC Savana, 2009 Chevrolet RV Cutaway, and 2009 Chevrolet Cutaway. However, it is still accessible from the selected car via links, so may be relevant.
- Inspect for the following conditions, which may cause a diesel oxidation converter (DOC) to degrade:
- Off Road Fuel or Red Dye Fuel
- Low quality B-20 fuel
- Fuel Containing high sulfur content
- Engine oil or coolant consumption
- Leaking fuel injectors
- Inspect the DOC for the following conditions:
- Physical damage or alterations
- Internal rattles caused by a damaged catalyst substrate
- Exhaust leaks before or after the DOC.
- If a condition is found, replace the DOC.
- If all exhaust system inspections are normal, replace the DOC.
IMPORTANT:
Perform the Repair Verification after completing the Circuit/System Testing.
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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.