I have an LBZ 2006. I have had the EGR valve replaced twice alreaDy when the engine was under warranty. Now I'm getting the same code again that I have an EGR issue. GM won't cover it.(125k) I've been driving my truck now for about four months with the check engine light on. I have seen NO drop off in performance or fuel mileage. Should I worry? To the best of my knowledge All this is for is to meet the emmissions standards.