The present study aimed to evaluate the effects of Automated Vehicles (AVs) with and without communication capabilities on traffic efficiency at yield sign-controlled intersections. When equipped with communication capabilities, the AVs may be able to take earlier decisions on whether they need to yield or not and this may affect, consequently, their travel time and queue formation at the intersection. Detailed models of intersection behaviour were developed for Baseline AVs (that use only their onboard sensors for perception and decision taking) and for Enabled AVs (equipped with communication capabilities). A microscopic simulation study was carried in a yield sign-controlled intersection, with varying traffic volumes and AV penetration rates. The findings support the expectation that the addition of communication capabilities may reduce the travel time and queue length at such intersections. The size of reduction and the number of vehicle routes affected seemed to attenuate as the AV penetration and traffic volume increased. The relation between the number of routes affected and traffic volume was not straightforward.