What kind of harm can happen to your vehicle when the EGR positioning is not positioned correctly?

The purpose of the EGR valve is to direct some of your exhaust gas right back into your intake. Hence the name: Exhaust Gas Recirculation. Sounds pretty ridiculous, huh? Well, exhaust gas actually helps your engine warm up more efficiently (so the valve is open when the block's cold), then the valve's supposed to shut off that exhaust intake when you're warm. If it stays open exhaust is always recirculated into the engine. It would be like taking your air filter off and driving continuously through a tunnel filled with exhaust. Nice, huh? The life, gas mileage, and horsepower of your engine are all reduced.