The Exhaust Gas Recirculation or EGR Valve, is vital to your car's emission controls. By recirculating a small portion of exhaust back into the engine, it helps to keep huge amounts of unburned fuel from being released into the atmosphere. To maintain your car’s efficiency, it is important that the EGR valve is working properly. If the EGR valve is blocked or malfunctioning it can cause your engine to run poorly. So, if your engine is idling roughly or accelerating poorly, ask your service advisor to take a look at your EGR valve. EGR valves may be cleaned, but once it fails, your only option is to replace it. If ignored long enough, a car with a bad EGR valve will not pass emissions. From a safety standpoint, there is a slight safety risk, because a failing EGR valve may cause you to stall in unwanted situations. From an environmental point of view, a failing EGR valve will cause harmful gases to be released into the environment.