You can take the egr vavle off and make sure the pintle in the egr vavle isn`t clooged with carbon ect
Using a handpump make sure the diaphram is working
If its a electronic egr you have to run a ground and voltage check at the plug in which you will need a scanner to work with .....some of these egrs vavles will get expensive as much as 3 or 400 dollars so a salvage yard might help
bg
January 2009