Among many types of wireless links, RFID presents the great advantage of using batteryless devices. Thus, applying in a maintenance and repair system, it is the cheapest, easiest to install non-intrusive solution, well suited for equipment of classical cars. This paper gives quantitative results stemming from an experimental and numerical study and allowing to estimate the limitation of passive UHF RFID tags for implementation of this solution. The gained information defines in particular the sensitivity threshold that should be reached by purely passive tags in order to run in this semi-confined geometrical configuration.