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Home >> GMC >> 2006 >> Sierra 1500 HD, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 1051 (Engine Controls And Fuel - 6.6L - DTC P02E7 To DTC P0699) >> DTC P0401 or P0402 >> Circuit/System Verification

Circuit/System Verification

WARNING: This page is about a different car, the 2008 GMC Sierra, 2008 GMC Cab & Chassis Sierra, 2008 Chevrolet Silverado, and 2008 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
  1. If DTC P003A, P0101, P0403, P0405, P0406, P046C, P0698, or P0699 are set, diagnose these DTCs.
  2. Using the output controls on the scan tool command the EGR solenoid to 10 percent.
    • If the actual EGR position remains stationary, replace the EGR valve.
  3. Inspect the exhaust system for leaks, restrictions, or for modification of the original equipment manufacture (OEM) part.
  4. Visually inspect for leaks between the MAF sensor and the turbocharger.
  5. Visually inspect for a restriction in the air cleaner or the air intake ducts.
  6. Visually inspect for a restriction in the turbocharger charge air cooler.
  7. Visually inspect for a restriction in the intake manifold.
  8. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.