P0161...what a mess

[Grabouss]

Alright folks, I'm pretty clueless now. I have a 2009 Dodge Ram 1500, 5.7 Hemi with a little over 100000 miles. My check engine light is on and the OBD2 dsplays code P0161, downstream oxygen sensor on the passenger side. I chsnged the sensor with aftermarket, didn't help. The check engine csme back in after abot 30miles. Chnged it again for a factory sensor, same scenario. I started feeling the wire and found 2 chaffed wires, fixed that and same scenario, light came on after 30 miles. Took it to the dealership who told me that the wiring harness was bad and needed to be changed, i ordered a new one and spliced it in the old one as far up the old harness as I could. Guess what! Same scenario. when I took it to the dealership, e mechanic also told me that the faulty sensor ran either too hot or too cool, can't remember which. I thought maybe I'd have a bad catalytic converter heating the sensor too hot (if that's even possible I don't know) so I checked the temperature of both catalytic converters. They both run around 540 degrees just before and just after the catalytic converter and about 470 degrees right in the middle of it. I don't know what else to look at or check. Any thoughts on what I should look at next?