آسیب نشیمنگاه یا دیافراگم شیر EGR

The recirculation valve's sealing seat eroded or its diaphragm split. It is mechanical damage rather than the carbon fouling that accounts for most faults here, and the distinction matters because cleaning will not fix it.

A damaged seat cannot seal however clean it is, so exhaust gas enters the intake continuously and the engine idles roughly with a hesitation off idle. A split diaphragm on a vacuum-operated valve is also a vacuum leak, which drags down every other device sharing that supply — so a set of weak vacuum actuators alongside a recirculation fault points here. Test the actuator with a hand pump: one that will not hold vacuum has a torn diaphragm, and the seat is judged by eye once the valve is out.