2011 Ram 3500 6.7 dsl.

I had codes for o2 sensor heater resistance in both o2 sensors. I checked and the sb-25-004-13 has been done. I also checked the sensors live data and they were not registering anything. So i replaced the sensors and now i can read the live data. Drive down the road and the truck drives great with the ses light off. Driving down the highway it comes back on. I read the codes and i got p0040. Does anyone have any ideas on what could cause this? Also with the p0040 i got the nox code.

Any help would be appreciated.

Thanks