need2 replace o2 sensor on my 2005 hondacivic si.says bank 1 sensor 1.which one?

thanks i appreciate it. I have a mechanic here at my work but he hasnt done a os replaceement in a long time. Out of curiousity what would a simple replacement for an o2 sensor cost? i have to get my damn engine light off so i can pass inspection. thats all i want to do and its turned into this whole big thing now that sseems like its gonna end up costing me way ore than i could have guessed. whats a fair estimate?

Not sure how much your part is till we look at it. I would like to make sure thats what it needs before we replace it. But here is a good link to get a ball park. http://repairpal.com/estimator/results yourmobiletechnician.com