You should get a CEL that tells you which bank, which sensor post cat that is the issue. If it's just one sensor on one side, move it to the other side and see if it follows. Then again, I have a '03 which may be slightly different than yours. I wonder if we both have just one sensor post the last cat so that it's common to both banks. I bet that's how it is.
I have Techstream if you need to use it. Just show up at another breakfast meeting and we'll hook it up. Although, given your appearance rate, might be 2019 since you blew your mtg wad for the year