This is an expected journey after the X5 was off the road for 16 months+. This thread is going to be a documentation of what clearing this is going to take. I have some reading to do and some testing to do. Probably some DEF cleaning to do as well though I checked the metering valve while installing everything. Could be the system is not happy with the old, possibly stale, DEF fluid. Draining it sounds like fun...
So, having completed my trans replacement and putting about 150 miles on it, I am pleased to say that it is driving beautifully. Shifts are smooth and clean. Going to do one drain/fill with fresh fluid as I want to clean the 88k mile trans out after it sat without plugs in the cooler line holes... but that's all for my trans thread.
For this thread... ~75 miles into testing I got an SCR code for inefficiency (4D16). I figured it was because it was going to take some driving for regens to occur and go back to operating normally. So I cleared it. Probably a mistake doing that. After looking at Tis a little more carefully, I should have run an SCR relearn/activation procedure after completing the work...
Here are the codes I am getting which include the dreaded 200 miles to no start condition. I am documenting this as a roadmap for others who end up with similar issues as it seems that good info is scattered across many threads and pages in those threads as well as across many different forums. That makes it a bit hard to follow jumping between 10 tabs in the browser. If anyone has any input by all means add it. I'll keep editing this first post until the issue is resolved and finish it off with a "SOLVED" in the title after complete.
For Google search purposes:
41F9 SCR system: System error and poor urea/water mixture quality detected
46F2 DDE: DeNOx system, function
4748 SCR system, warning and deactivation scenario: Warning stage 2
474C SCR system, warning and deactivation scenario: Warning level 1
4D16 4D16 SCR system, efficiency