The exhaust Gas Recirculation Valve, or EGR valve for short, recirculates finely metered quantities of exhaust gas to the engine intake system for increased engine efficiency, reduced fuel consumption, and lower NOx emissions.
EGR valves operate in a hostile environment so over time will experience wear and tear. However, the single biggest cause of failure is the buildup of carbon particles from the exhaust gases along the EGR and intake system passages. Over time this will clog tubes, exhaust gas channels, and eventually the valve’s plunger mechanism, causing it to either stick open or close. Failures can also be caused by a rupture or leak in the valve diaphragm.