03 v6 O2 sensor bank 1 sensor 2?

which sensor is this the one before the cat. or the one after?
that the code i have bank 31 sensor #2

Bank 1 is the same side of the car as the #1 cylinder. Sensor 1 is always before the cat, sensor 2 is always after the cat.

thanks much!

has 4 sensors was not sure thanks again

do not work on chryslers much...gm V6 motors are 1 3 5 front 2 4 6 rear
chrysler 2 4 6 front 1 3 6 rear,,, sucks because bank 1 sensor 2 is the worst oxygen sensor to get at!!!! still working at it!!! and thats the sensor i need to change