But if the error was serious, even though it was cleared, it would have returned. You can clear CEL's all day long, they will keep coming back until the problem is fixed. So he went a mile and it cam on, he goes back, they clear it and it didn't come back did it? So correlating the CEL to the engine failure cannot be done either without knowing what the error code actually was.

OP, when you took it back for the CEL, how long did BMW have the vehicle before returning it to you and saying it was nothing?