My 2019 f150 is being towed as im writing this.
DEF fault
hope warantee covers it , if not i may just do a complete delete
im in Canada so no emissions checks here

 

My money says NOX sensor 1_1. I've replaced a couple of them on these F-150 3.0L diesels. Other than that, these 3.0L diesels have been relatively trouble free.

 

Oh no, sorry to hear about your 2019 F150 getting towed due to the DEF fault! Hopefully, the warranty will cover it for you. If not, that complete delete option might be the way to go, especially with no emissions checks in Canada. Hang in there, and hopefully, you'll get your truck back up and running smoothly soon!