If you say you have tried plugging the O2 sensors into each other and therfore eliminating the fault to be with the sensors it must be the wire for Bank 1 sensor thats at fault? do you have a wiring diagram of the ECU. Maybe you can un-plug the wire from the ecu and run a new temporary wire to the ecu from bank 1 O2 sensor and see what the results are?

Was the voltage reading coming from the sensors? was it pulsating or a constant? Everytime i have checked O2 sensors the signal is pulsating when they are working correctly