Why do EGR valves fail?

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.