Just a quick shout out and thank you to Astrofriend... I found this thread while trying to diagnose a 2004 I rescued with a Check Engine Light and the exact codes. I was about to drop time and money on O2 sensors then I am certain now still end up taking to a shop. After reading this I found out that the previous owner had done some work under the car and disconnected the downstream sensors. I swapped the cables and immediately the car ran better, no CEL in 125 miles and it passed emissions.
Thank you!