O2 Sensor Location

[dudeinthething]

I got a P0155 code O2 sensor Heater Circuit Malfunction. Bank 2 Sensor 1. Does anyone know the location of this O2 sensor. I assume that bank 2 is the drivers side, but I looked under the car and found on after the pre cat and one on the pre cat.
Please chime in if you know.

 

[zintkala]

Upstream. Might as well replace both of them as they seem to fail at around the same time. Just an FYI, ask at your auto parts store to see what they stock, the Bosch universals run $20-30 more than the Bosch factory replacements and buy the O2 sensor socket for a few $$$. Makes life much easier, very simple DIY repair.