I had these exact codes. Replaced the primary oxygen sensors a few wks ago but im still getting the fuel mixture codes even now. Does it even on stock tune. With procede aggressive maps I'm maxing out fuel trims even on pump gas.
Cobb E40 PROtune by Jake@PTF/RR catless DPs/aFe DCI/ETS 5" FMIC/Alpina B3 TCU flash/BMW Perf. Exhaust./BMW Performance Style 313s/M-Tech Rear