Nissan Sentra Gxe 2002 check problem

Good I have problems with the Nissan Sentra Gxe 2002 Motor 1.8 I put the scanner and I have a bad oxygen sensor but this uses 4 the port 2 bank 2 bank 1, but how can I identify this sensor thank you

Hello: look that car has 4 sensors, 2 are oxygen and 2 are from the catalyst, those above are oxygen, in the scanner they appear as O2S1 Bank 1 or Bank 2, that is, sensor one of the bank one or sensor 1 of Bank 2, the banks are distingu Sensor one from Bank one, is the front sensor, if you mark sensor 2 of the bank one is the sensor below the front, and so on.