P2CAB and P2CA7=lambda/precat o2 sensors, my car threw the same two codes when mine went bad a few months back. The car will start to misfire on cold start and generally drive poorly, which makes perfect sense seeing as how it'll have a tough time getting AFRs correct. If you're under warranty just take it in (unmodded obviously), if not, O2 sensors aren't too brutal from a cost standpoint. Any competent shop can take care of it quickly.
E88 N54 Alpinweiss/Coral Red/Motiv HTA 3586r Tial .82AR/Motiv Port Fuel/Meisterschaft Race/Berk Resonated/ER CP/Synapse/VRSF FMIC/Rob Beck PCV Valve + Cap/ST Coilovers/M3 FCA + Tension Rods/M3 Subframe Bushings/M3 FSB/AA Strutbrace/DINAN Camber Plates/Apex ARC-8/Project Kics/VAC Hubs/Rogue Transmission Mounts/Alpina TCU Flash/Icarbon/#Tee CF Stuff/Kerscher/BMW Performance