[MrE]

UPDATE AS OF LATE 10/19: I've been in touch with Cummins Tech Support, who dug deep into my engine's S/N. Interestingly, the bulletin I found has vanished without cause, or ANY type of history...Terrific.

Sooo...here's the scoop based on what I know:
These dosers can be damaged by improper purge settings. Cummins apparently addressed that issue several years ago with an ECM update. This must have cleared the issue up enough for them to remove the recommendation for annual Doser replacement. HOWEVER, if you're like me, and have a doser that is damaged, the ECM update doesn't do you any good, and the doser will need to be replaced.

Of course, if you have the newer X15, the ECM is a newer version and you should be able to steer clear of this issue. In fact the DEF Doser is nowhere to be found on the 2021 X15 Maintenance chart; thanks to Tony Pope for pointing me in that direction!

I hope this helps, rather than alarm or confuse. Bottom line, if you have an older ISX, get your ECM updated, and I would STILL have them check the DEF Doser just to be sure it's functioning correctly.

Obviously an update to the ECM won't repair a damaged part, but you should take your own advice and get your ECM updated. Use rawze.com to instruct you how to update your ECM so you don't mess anything up.