2% +/- is not crazy for LT and ST fuel trims. When you get over 5% and 10% you have an issue. I believe codes trigger on BMWs at 10% +/- LTFT. At least that's how it was on the M54.

Must admit I've never really worried about fuel trims. If a code popped for one it was usually a vacuum leak. O2 sensor codes were usually heater circuit errors.

__________________
2005 X5 4.4i Build 04/05 Maintenance/Build Log
Nav, Pano, Sport (Purchased 06/14 w/ 109,000 miles) (Sold 8/15 w/121,000 miles)

2006 X5 4.8is Build 11/05 Maintenance/Build Log
Nav, DSP, Pano, Running Boards, OEM Tow Hitch, Cold Weather Pckg (Purchased 08/15 w/ 90,500 miles)

2010 X5 35d Build 02/10
Nav, HiFi, 6 DVD, Sports Pckg, Cold Weather Pckg, HUD, CAS, Running Boards, Leather Dash, PDC, Pano (Purchased 03/17 w/ 136,120 miles)