I think you may have misunderstood what he said, although im not sure. VAG stands for Volkswagen AG and they (also Audi) use these numbers for all diagnostics. There are no VAG numbers on Benz or BMW diagnostics. Maybe he is a volkswagen mechanic and used this as a term of phrase. Maybe what he was trying to say was he cannot access the fault codes.My mechanics has run diagnostics and has said he cant access the vag numbers, obviously this is something only MB can do.