We report on the strong interaction between graphene and intercalated cobalt revealed by scanning tunneling spectroscopy (STS). A significant difference between pristine graphene and Co-intercalated graphene is identified at high bias voltages in the regime of field emission. For MLg/Co/Pt a resonance is observed at 3 eV which is not visible for pristine graphene. Additionally, we observe a change of the phonon energy upon Co intercalation. Our STS results indicate that the Dirac point will not be preserved for graphene on Pt(111) if a single atomic layer of Co is intercalated.