The document discusses common EGR valve problems in Audi vehicles. The main purpose of the EGR valve is to reduce nitrogen emissions by recirculating exhaust gas back into the combustion chambers. Common problems include rough idling due to the valve getting stuck open or closed, reducing fuel mileage and engine performance. A stuck open valve can also cause the engine to stall while idling. Neglecting EGR valve issues can affect the exhaust system and cause the engine to burn more fuel and produce a gasoline smell. Owners experiencing these problems should consult a reputed mechanic.