A FAW Volkswagen Kai Di multi functional commercial vehicle with a mileage of over 270 thousand km in 2005. User reflection: the car can't start. Inspection and analysis: maintenance personnel detect engine control unit and find it impossible to enter. Detect gateway control unit and find bus fault prompt. Viewing the 130 sets of data of the gateway control unit, it is found that the comfort system data bus has a state of 0.