1st thought, would be to use a BMW scanner, not a generic one. if bank 2 after cat was running lean, it would not set this fault, it would be a Cat Efficiency fault, or Cat Conversion fault.

also there is a software calibration error in the DME that can cause these o2 sensor faults. E53 X5 with M54 (MS43) from 09/00 up to 09/03