there are upstream and downstream o2 sensors. you need to know which one specifically is bad.
did you get a real diag or a free code pull. if you got the code pull, have the diag before you replace it. a code never identifies a bad part just a failed system.
what code did you have??
I put a k&n air filter on it and now I am getting 50miles per 1/4 tank of gas. That is horrible, I know the oxygen sensor will cause extreme gas intake and thought it might be the reason.. I haven't had the sensor tested yet. If you have any other reasons for this I would be very grateful.