A 2D finite element model is developed to simulate the protection of active protective coatings in a defect. The leaching kinetics, inhibitor-electrolyte reactions and electrochemical surface reactions on homogenized AA2024-T3, are considered. Changes in local oxygen distribution, pH, and current density over time are validated using surface scanning micro-probe techniques. The limitations posed by the prediction of surface current density at the metal interface using a FEM model with a homogenized microstructure are identified and addressed. The validated FEM is then used to predict inhibitor concentration and pH dependent on the initial inhibitor pigment concentration in an organic coating.