A Volkswagen Jetta car with a mileage of over 300 thousand km, equipped with Volkswagen's AG4 01 M 4 speed electronic controlled automatic transmission, 2002. Car owners reflect: this car sometimes hanging in the D position, after normal driving, such as traffic signal light pedal brake pedal parking, again starting when the vehicle can not drive, at this time the transmission pole placed in 3, 2 and R position can not drive, and the transmission lever in the 1 position can drive. According to the phenomenon described by the user, the technician can experience the real fault of the car by himself. Because this fault does not appear frequently, it can get the characteristics of the fault for a long time. When the automatic transmission failure occurs, it is exactly consistent with the fault phenomenon described by the user.