The automotive system domain are in increasing motivation with benefits by using the x-by-wire technologies, which employ new electronic devices to provide for automobile system more facilities during processes at development, production, usability and maintenance. Considering at automobile user domain point of view, the next generation of automobiles can give users more comfort, safety and flexibility. However, for the safety critical applications at automobiles have as requirements the use of distributed embedded systems and fault tolerance methodologies where in communication infrastructure need to offer fault-tolerance communication services. Several researches regards fault tolerance communication systems for automotive domain are now in progress and a strong convergence in use of the Flexray technology is noted for the automotive community. The Flexray is one of the communication systems that had been proposed and available at AUTOSAR standard. Flexray is a communication system with high data rate, deterministic and fault tolerant protocol that was developed to fulfill the requirements for next-generation automotive systems. Safety critical applications will be introduced in automotive system together with non safety critical application, being necessary a communication service that is shared and flexible, at system design. We focus in this work a new approach of bus-guardian for Flexray communication system, considering star and hybrid topologies, which increase the system fault tolerance by implementing specific filtering function in order to guarantee that the system will tolerate the failure modes stated in fault hypothesis.