I am trying to locate the heated oxygen sensors on my 2002 Hyundai Sante Fe V6 2.7

I think that there are four sensors, the code I am getting is P0057 -- H02S Heater Circuit LOW (BANK 2,Sensor2)

I Can locate 2 sensors on the front side of the engine and 2 on the back (firewall) side of the engine. I just can't figure out which is the sensor I am getting the code from. The sensors at the part's house are anywhere from $59 to $120 each depending on which one.

Any help would be appreciated