This study examines the accuracy of solving the multi-component equations for a Proton Exchange Membrane Fuel Cell (PEMFC) by using a Computational Fluid Dynamics (CFD) technique. This technique uses an approximated multi-component (AMC) model with a correction term that guarantees the overall mass balance. Accuracy is assessed by comparing the species concentration computed with the Maxwell–Stefan and the corrected AMC models. This comparison is important because the structure of some CFD programs does not permit the direct use of the Maxwell–Stefan equations and this leads to confusion in the literature and to implications that CFD predictions are not accurate because a different set of transport equations and mixture diffusion coefficients are used. Here, it is shown that this controversy is ill-founded because the maximum error between the two models is less than 5%. Thus, the use of the corrected AMC model is appropriate for PEMFC applications.