The exhaust gas recirculation (EGR) system has become a central part of modern engine design as a result of government legislation to lower exhaust emissions. The system helps to moderate nitrogen oxide (NOX) emissions produced in the combustion chamber when the engine’s temperature is high, by introducing a proportion of its exhaust gas into the intake air, thus lowering the temperature and, in petrol engines, it also reduces fuel consumption if it is operating under partial load.