Diagnostic Aids
WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 2003 GMC Yukon XL, 2003 GMC Sierra, 2003 GMC Cab & Chassis Sierra, 2003 Chevrolet Suburban, and 2003 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
Inspect for excessive deposits on the EGR valve pintle or seat. Remove the EGR valve and check for deposits that may interfere with the EGR valve pintle extending completely or cause the pintle to stick.
If DTC is determined to be intermittent, see INTERMITTENT CONDITIONS under SELF-DIAGNOSTIC SYSTEM.