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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 P0401 or P0402 >> Circuit/System Verification

Circuit/System Verification

WARNING: This page is about a different car, the 2009 GMC Sierra, 2009 GMC Cab & Chassis Sierra, 2009 Chevrolet Silverado, and 2009 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
  1. Verify if DTC P003A, P0101, P0403, P0405, P0406, P046C, P0698, or P0699 are not set.
  2. Ignition ON, observe the Desired EGR Position and the EGR Position Sensor parameters. With a scan tool, command the EGR solenoid to 20 percent in 5 percent increments. The Desired EGR Position and the EGR Position Sensor parameters should respond and remain within 3 percent of each other with each command.
    • If greater than the specified range or the EGR Position Sensor parameter does not respond and remains stationary, replace the EGR valve and gaskets.
  3. Engine running at idle speed, perform the following:
    • With a scan tool, command the EGR solenoid to 25 percent.
    • Increase the engine speed to 2,500 RPM. The engine should run rough.
  4. Operate the vehicle within the Conditions for Running the DTC to verify that the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
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