Started getting tail light error this week on the driver side. Opened up the inside of the tail light assembly courtesy of Uncle Fjester's youtube video here:
https://www.youtube.com/watch?v=r2ibvjlodLk
Anyway, looks like I might have the same problem as him; intermittent connection issue on the black and red wire that goes into the small circuit board inside the assembly.
I don't know if this is an issue due to the bad wire/ bad circuit board, or bad tail light seal that allowed moisture inside.
But the tail light unit is held on so tight that I can't budge it even after removing the 8mm nut and the black plastic assembly ( the same one the OP took off).
I did find that wiggling the black / red wire introduced power into the tail light, but i know it won't hold reliably.
So the question is, does the 2012 E70 have a different tail light assembly that requires more than the removal of the 8mm nut to take off the entire unit?
Uncle Fjester's E70 is a 2007 model.