Leak diagnosis method of exhaust gas recirculation using electric lead signal

PURPOSE: An EGR leakage diagnosis method using a commutation signal is provided to judge the leakage of the EGR valve according to the electric current apply between a valve housing and a valve and to supply data which is very useful for minutely controlling an EGR valve. CONSTITUTION: The leakage of an EGR(Exhaust Gas Recirculation) valve is judged according to the electric current apply between a valve housing(20) and an actuating rod(10). The actuating rod, a valve and the valve housing constitute a machinery exhaust gas recirculation valve. The actuating rod flows in the axial direction. The valve is connected to an end of the actuating rod, and opens and closes a valve seat. The actuating rod is installed in the valve housing. A first connection line(31a) and a second connection line(31b) are connected to the actuating rod and the valve housing and ends thereof are drawn to outside. A power supply unit(30) is connected to the first and second connection lines. A signal is detected by a signal detecting unit(32) electrically connected to a power supply unit.