OK.. just an update. Limped it to the dealership. 12 miles from the 55 MPH limit. They swapped out the nox #1 sensor, reflash, and did the regen on the recall. Still wouldn't come out of limp mode, wouldn't pass DEF quality test. And, still no codes.
Two of the guys took it for a spin with the laptop and saw that nox #2 was not working. Service quoted me $1300 to replace that and do the suggested radiator and trans fluid flush, only about $900 just to do the nox sensor only (that was 3 hrs labor). I waited a couple of days so I could call and speak to them without yelling.
I was just going to go get it and order the sensor online. But, they backed off of their list price on the part to $350 and I OK'd 2 hrs labor. So $600 plus tax and we're down the road.
The dealer is 45 mi away so that was a factor. If I paid $125 for 1 hr diagnosis and swapped it out at home and that fixed it and cleared the warning out I'd be good. But if they needed to do something for it to do the DEF quality test then I'd need to bring it back. I didn't know if the "DEF quality test" is just part of normal operation of the motor or if it was initiated by them. They implied I'd still need to bring it back after I changed it myself. I know this is not always the case and I'm sure they don't know if I'd need to bring it back either.