[JKoffler44]

I am working on a 2000 Ford Mustang V6 3.8 L for a friend. He came to me with the check engine light on. I scanned it and got a P0141, Oxygen sensor heater malifunction (bank 1 sensor 2). I am wondering if anyone can give me any info. on this so I know if I can do the job myself or not. Where is this sensor? I am guessing it is the one after the catalyst? Is it a pain to replace?
thanks!