OBD2 one points two connecting line extension cord. Effect is that if the current OBD interface has been occupied by other equipment, CAN use it to separate two interfaces, and CAN use read data don\'t interference. If both sides is not supported by the data to the car equipment, car does not support double equipment communication at the same time, if only CAN take electricity or read data CAN be used at the same time. Does not support auto fault code detection at the same time. Can separate testing communication. Tired with reading data flow (sending and receiving data).