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Home >> GMC >> 2006 >> Sierra 1500 HD, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 1375 (Engine Controls And Fuel - 6.6L - DTC P02E8 To DTC P1247) >> DTC P0420 >> Circuit/System Testing

Circuit/System Testing

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    IMPORTANT: Perform the Repair Verification after completing the Circuit/System Testing.
  1. 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
  2. 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.
  3. If all exhaust system inspections are normal, replace the DOC.