A couple of months ago my uncle and I replaced an oxygen sensor in my car. banks II sensor I i think it was (cant remember exactly) the front sensor on the passenger side of the vehicle. I had a "mil" light and took it in for a scan, sensor was bad, the place i bought the car from paid for and sent me the new sensor, which was very generous of him to do, cool guy actually. but we changed the sensor, the "mil" light cleared, took it back in, no codes were present. Now 2 weeks ago i took it back in to get it scanned again at our local aamco. pretty much one of the few places where i am from that i could get it scanned.
And their scanner pulled up
# 17539
Banks II Sensor I
Resistance Too High

Does anyone know what that means?

 

Make sure this O2 sensor has a good electrical connection.

 

Just replace the driver's side before cat O2 sensor.

 

Yep - I saw your original posting saying bank 2 and that you changed the passenger side sensor - that's bank 1. Take the one you removed from your passenger side, and swap it into the driver's side. Clear the code and see if it comes back. Since your original code said bank 2, and you changed the passenger side, the sensor you took out should be good. Use that and see if the code goes away for good.