Check engine light

The check engine light recently came on. When checked, it has a code of P0171. I was told that this meant a tune up. I was also told that this is an oxygen sensor issue. Is this something that can be easily replaced or do I need to take it to a dealer.

Its not the hardest thing in the world to do I would either use a helms or a haynes and see if you could do it on your own.