FWIW my car threw a P29e1 a few weeks ago after running an ethanol mixture, the mix was only about e30 total so it wasn't overly aggressive..I scan the car for codes once every week or two, and this code popped up. No CEL/SES light was thrown at any time, and the car drove completely fine, in fact I believe I had data logged the night before to see how the car liked the ethanol. Code was cleared and has never come back, so i'm not particularly concerned about it.
E88 N54 Alpinweiss/Coral Red/Motiv HTA 3586r Tial .82AR/Other stuff...652WHP
F30 N55 XDrive EBII