The U0101 OBDII fault code is a generic code in most brands and models of vehicles. It indicates that the TCM (Transmission Control Module) has no communication with other vehicle control modules.
Usually, the Control Area Network (CAN) is the most used circuit for the communication of these modules. Without this network, it is not possible to carry out the information exchange that the modules perform, nor is it possible for a scanner to get information from the vehicle.