CDI Mercury / Mariner M.E.D.S. Marine Engine Diagnostic System (Mercury Ver. 3.0) M.E.D.S., Marine Engine Diagnostic System, is an easy-to-use advanced software package specifically developed for troubleshooting marine engines. ; Benefits from M.E.D.S. Reduce Debug Time; Improve Accuracy; Run & Print M.E.D.S. check report; Product Description: M.E.D.S. Mercury System; Compatible with Mercury OptiMax and 4-Strokes through 2010; Most 2-Stroke EFI; Mercruiser MPI; Not compatible with Yamaha built 4-Strokes; Replaces: 531-0118M;