IF there is a circuit malfunction it does NOT mean lean. It means the O2 is fried. And seeing as it it Bank 1 Sensor 2, it's indeed the lower one that's done.
don't assume that O2 codes mean lean/rich or worn out.
IT's best to post the code and let us OG's decipher it than come to a guessed conclusion like you did.
I would swap out the lower O2, but I would buy it (234-4609) from sparkplugs.com for $45!
http://sparkplugs.com/results_app.asp?AAIA=1362226&mfid=3 
