Which O2 Sensor?

[Dutchie3719]

I have a california (50 state) 1999 I30. I'm wicked confused on which O2 sensor is Bank 1 Sensor 2. Also does anyone have a p/n for it? I'm trying to buy a new one off rock auto or amazon (cheapest place I've ever found an O2 sensor) I'm used to inline motors, so this whole v-thing is just throwing me off. I'd have assumed left bank, rearmost plug, but it seems that they combine into a single header and have two sensors post-cat. Which should I replace? I think (at the office so I'm guessing) that the code thrown was P0139?

Cheers,

Dan

P.S. New to forum, still learning best way to search! Don't kill me!

 

[Dutchie3719]

Useful Relevant Image

http://infinitihelp.com/diy/i/projects/infiniti_i30_o2_sensor_identification.php

Not sure if I need to replace the:
Bosch 13760 (Red Wire)
Bosch 13348 (White Wire)