2015 RAM 3500 - 45,000 miles.

A message popped saying, "5 MPH Max Speed in 131 mi, Service DEF System See Dealer".

I have no codes (outside of some left door panel or something other).

Hooked up OBDII and see there were 88.66 lbs of DEF Pressure so the pump is working.

I tried clearing codes, but it remains.

Any thoughts on how I can get this message cleared?

It goes without saying; I need my truck later this week.

I called the Dealership, and they said they're 3 weeks behind.

Any thoughts?

Thanks.