The evolution of System-on-Chip (SoC) designs involves the development of non-volatile memory technologies like Flash. Embedded flash (eFlash) memories are based on the floating-gate transistor concept and can be subject to complex hard defects creating functional faults. In this paper, we present a complete analysis of a particular failure mechanism, referred as disturb phenomenon. Moreover, we analyze the efficiency of a particular test sequence to detect this disturb phenomenon. Finally we conclude on the interest to develop new test infrastructure well adapted to the eFlash environment.