egr= exhaust gas recirculation.. esentialy its suppose to open up at high way speeds to theoretically trick the engine in to running like a smaller engine to save on gas.. with it plugged you mite lose a mile or 2 per a gallon.

 

i just don't like the idea of exhaust being dumped into the intake, sounds kinda odd to me, but then, im pariniod

 

mines blocked off.....get a code every great once in awhile