A method based on Monte Carlo simulations (MCS) is developed to assess the impact of manufacturing tolerances on the performance and reliability of solid oxide fuel cells (SOFCs). Computational fluid dynamics (CFD) simulations of the anode gas diffusion layer (GDL) are carried out for a set of deformed geometries. An automated code allows generating standardised deformations in a random manner on the original meshed geometry taken as input. In the scope of this study, the fuel flow uniformity is taken as the indicator of the performance and reliability of SOFCs. Statistical sensitivity analyses are carried out to assess the impact of dimensional tolerances on both repeat elements individually and a whole stack. The implemented method is evaluated with two standard GDL configurations. Results show that the sensitivity to thickness variations is predominant on the sensitivity to in-plane deformations of channels. Besides, the magnitude of sensitivity largely depends on the GDL configuration and on the extent of the deformation, too. In addition, negative effects of deformations are shown to be exacerbated in stack configuration. The method proved successful to quite quickly get insights on the quality of GDL configurations with respect to dimensional tolerances.