What is an EGR valve?
An EGR valve is the main component in an engine's exhaust-gas recirculation system. Petrol and diesel engines deliberately capture some of their spent exhaust gases and flow them back into the intake alongside fresh fuel and air. That might sound counterproductive but it helps improve overall efficiency and reduce knock – times when your fuel-air mix ignites before you'd want it to. All modern cars have an EGR system of some kind, and many contain an EGR valve to separate out the desired amount of spent exhaust gases to recirculate.
Over time, an EGR valve can become clogged with soot and other particulates from the engine. If this happens, your car will start to run rough and see reduced power and fuel economy. You can pay a specialist to clean your EGR valve or, if the problem is serious enough, replace the valve completely.
