FYI: After much ado, and several different opinions we finally got our hands on (wouldn't let me have it or even get a copy) of the dealer code book. In there it tells you exactly what it is. I've seen it here but also read all kinds of other stuff.

P1131 does indeed means #1 Bank 1, which really means driver side, front side, oxygen sensor!!! If that is the problem and you change it, you'll know immediately because the CES goes off on it's own on the restart!


PS. Don't buy the cheap brand either!