Position sensor for a mechanical device, including: an optical emitter arranged for projecting an incident radiation on a positioning track of the mechanical device provided with multiple optical sections; an optical detector arranged for detecting a reflected radiation coming from the positioning track and for generating a corresponding measurement signal; an electronic processing unit arranged for calculating, on the basis of such measurement signal, a reflectance value indicative of the reflectivity of the zone of the positioning track hit by the incident ray so as to distinguish the different optical sections of the positioning track. The position sensor also comprises a signaling module arranged for sending a warning signal as a function of the reflectance value, in order to provide to the user indications relative to the level of deterioration of the optical sections of the positioning track.