RFID systems are complex hybrid systems, consisting of analog and digital hardware and software components. RFID technologies are often used into critical domains or into harsh environments. But RFID system is only based on low cost equipments which then do not allow achieving robust communications. All these points make the on-line testing of RFID systems a very complex task. Thus, this article proposes the on-line characterization of a statistical system parameter, the Read-Error-Rate, to perform the on-line detection of faulty RFID components. As an introduction to the on-line testing of RFID systems, a FMEA first describes the effects on these systems of potential defects impacting the communication part. Second, a SystemC model of the RFID system is discussed as a way to evaluate the proposed test solutions. Finally, the way the maximal Read-Error-Rate can be determined using system-level simulation is explained.