An original method of determination of the local orientation of electric field together with standard 4-probe resistivity measurements were employed to investigate the microstructure of an automobile component (a gear) made by a powder metallurgy process; this study was accompanied by image analysis of scanning electron microscopy and optical microscopy observations. The distribution of the observed electric current lines clearly reflects the local anisotropy and fractures in the material. It was found that the electric resistivity in the specimens studied is extremely sensitive to the material porosity. It was shown that none of the existing theories of the electric conductivity of composite materials, starting from the Maxwell theory and including the effective medium models, is capable of explaining the observed super-sensitivity. A new approach is developed, taking into account material anisotropy. The results of this modelling have shown a good agreement with experimental results. The new method of electric field mapping may be recommended to investigate other structural materials. The model developed might be useful, in particular, to understand the influence of pores on mechanical properties.