I've been looking for a low mileage E550 to purchase. I found one that has a
manufacturer buyback in the vehicle title history. It was repurchased by Mercedes because of a starting issue. There's paperwork from Mercedes to verify the repairs. Apparently, the Mercedes dealer replaced the engine control unit to rectify the issue. What does that mean and how serious of an issue is that? The car only has 21K on it. Thank you in advance to anyone who can help me with this issue/question.

 

Run, don't walk, away. Think about it. Mercedes builds cars that have known head gasket issues (104 engines), wire harness issues (92-95), evaporator issues (90's), spring perch issues (90's and 00's), radiator issues (03/04 C32), heat soak issues (C32), dashboard issues (00's, just about every one built), never-change-the-oil-transmission issues (since rescinded, but those loyal customers who followed Benz instructions to the "t" are now having transmission issues) and walk away from the problem, with no help to the customer. And I think I've only mentioned a small portion of the crap these clowns put out.

You are talking about buying a highly complex electronics nightmare, that Mercedes actually agreed to buy back. It has to be a nightmare.

A cheap Benz is the most expensive car you will ever own.

If you "need" a Benz, go find one that has records to prove it has been maintained anally, in your price range.

Forget the cheap deal.