A mileage of about 130 thousand km, the model 211 is the 2009 Mercedes Benz E240 car equipped with 722.6 automatic transmission. User response: the transmission often does not respond when the vehicle changes gears with shifting gears. Inspection and analysis: the maintenance personnel tried the car and found that the gearbox worked normally without shifting gears. When the vehicle is running at low speed, the gear is also normal. The problem is only from high speed to low speed. The rule of repeated trials is that after the deceleration, if the gear is reduced, the gear will change from D to 4, which means that the transmission is actually reduced from 5 to 4. At this point, the actual gear is the 3 gear, so that no response to the transmission is reasonable. It seems to be a matter of control procedures. According to the technical bulletin, Benz Corp has made updates on the control procedure for this problem. In the new program, when the driver decreases the gear with the pick, the transmission will be changed according to the previous shift. For example, when the vehicle is running at 30 km/h, if it is 3 gears at this time, then the gear will be changed to 2 gears when the gear is reduced. In the old program, under the same circumstances, the gear can only be reduced from D to 4, that is, the reduction from 5 to 4, so there is no sense of shift. Troubleshooting: update the transmission control program, confirm the trouble shooting.