Which oxygen sensor connects to bank 1. Is it the front or back?

Hi, My 2001 Windstar was pulling these codes from the OBD: B1234- Mirror Switch(mirrors are working fine), B1236 - Window Feedback Loss of Signal(I do have a non-functional rear vent window) , U1262 (Ihave no idea what this is),
and PO171 - bank 1 system too lean.

Can you tell me how to get the Monitor back up quickly (I've cleared them) and which oxygen sensor relates to "Bank1"?

Thanks,

Victor