My sequence was included in the initial post, but the repairs were:
replace EGR cooler
replace Nox sensors
replace faulty EGR cooler (it broke apart)
replace catalytic converter

BMW got involved and determined to replace the cc this time around. They put almost 200 miles on my vehicle in about a week and a half trying to figure it out. Apparently it was not going into regen mode. I have no idea what codes were pulled. My car is still under the 7/70 emissions warranty in PA so I'm enjoying the luxury of free repairs...though my days of that are numbered.

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16 X5 50i


prior:
12 X5 35d
06 X5 3.0
06 Z4 3.0