The exhaust gas recirculation valve, more popularly known as an EGR valve, is a component of your vehicle’s emission control system. The EGR valve helps your engine to run more efficiently, consume less fuel, and put out fewer emissions.
The EGR accomplishes this by recirculating specific amounts of exhaust gases into the intake system and ultimately back into the combustion chamber. When that happens, the chemical makeup of the air entering the engine changes, decreasing the amount of oxygen so that combustion temperatures are reduced. In the process, less of the hazardous nitrogen oxide gas byproduct of combustion is produced. This allows for a cleaner and more efficient exhaust system.
EGR valves can be electronically controlled or vacuum operated, depending on your vehicle make and model.