The EGR valve helps your car more efficiently and completely burn fuel by recirculating a portion of your exhaust and running it through the combustion process again. These results in a cooler, more complete burn of the fuel which decreases you car’s noxious emissions by prohibiting the formation of some harmful gases. The EGR valve first appeared in automobiles in 1972 to counter this phenomenon. EGR valves basically do this by sending some of the exhaust gas through the intake manifold back into the cylinders. Because exhaust gas most often doesn’t burn, it stays and takes up space in the combustion chamber and lowers the temperature there. Older vehicles used to have mechanical engine EGR valves, but the newly manufactured ones have electronic EGR valves.