A regular structure and capability to implement arbitrary logic functions in a two-level logic form have placed crossbar-based Programmable Logic Arrays (PLAs) as promising implementation architectures in the emerging nanoelectronics environment. Yet reliability constitutes an important concern in the nanoelectronics environment, necessitating a thorough investigation and its effective augmentation for crossbar-based PLAs. We investigate in this paper fault masking for crossbar-based nanoelectronics PLAs. Missing nanoelectronics devices at the crosspoints have been observed as a major source of faults in nanoelectronics crossbars. Based on this observation, we present a class of fault masking approaches exploiting logic tautology in two-level PLAs. The proposed approaches enhance the reliability of nanoelectronics PLAs significantly at low hardware cost.