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 pintle or seat. Remove EGR valve.
Inspect for deposits that may interfere with the EGR valve pintle extending completely or may cause the pintle to stick.
If the condition is intermittent, see INTERMITTENT CONDITIONS under SELF-DIAGNOSTIC SYSTEM.