[JimD]

I do not personally understand or accept the "BMW specific code" discussion of this thread. If your check engine light is on, there should be codes out the OBDII port. That is a U. S. requirement, not optional for manufacturers. They cannot put out some codes and not others. Any OBD code reader will find codes that are present. It may not give you an explanation of what the code is for but you should be able to find that via the internet. I have a separate code reader and a phone/tablet application called torque. I prefer the latter but neither has had any issue on any car. I've never read of an experience that I would agree justifies the brand specific code arguments supporting purchase of a specific brand of code reader.

I had a problem with the bulb - only - in one of my tail lights. I have a 2009 e88. I bought a new tail light for about $100 from parts geek. I've since seen an explanation and a youtube showing how a printed circuit in the tail light can be replaced solving the problem. That would be cheaper but the new tail light fixed the problem. I never got a check engine light from it, however.