This work focuses on carbonation-induced corrosion in concrete. This paper presents specific experiments which were developed in order to assess the influence of both pre-existing oxides layer at the surface of the steel bars and steel–concrete interface condition on active corrosion. Two types of active corrosion are studied: Microcell corrosion and galvanic corrosion. Results show that pre-existing oxide layer contributes to reduce both galvanic and microcell corrosion. Steel–concrete interface defect leads to a strong increase in galvanic corrosion but does not affect significantly microcell corrosion in carbonated concrete. The quantity of pre-existing oxides is highly scattered and these scatters can be superior to the mass of new oxides formed during relatively short-term corrosion tests in natural condition which makes mass loss analysis very difficult.