Where is egr valve on 2004 Chevy trail blazer?

The EGR valve on a 2004 Chevy Trailblazer is located on the back of the intake manifold. It's often a bit difficult to access and you'll likely need to remove some components to get a good view and reach it. Because of its location and potential for heat, it's highly recommended you let a professional mechanic handle replacement if you're not comfortable working on engines yourself.