While driving across northern Arizona in December I got a service DEF system see dealer alarm, it cleared after a few minutes, then I got 5mph max speed in 150 mi see Dealer alarm which stayed in. I stopped and checked maps and panicked when I realized I was over 200 miles to the nearest dealer and it was a Saturday afternoon. Continued on 70 miles to where I was planning to stay overnight and picked the furthest town I could get to and get towed from the next day. Was pulling a travel trailer so was going to be a real mess. Next morning started the truck and no alarm, haven't seen it again. At that time I didn't realize that once I turned off the truck it was going to be limited to 5mph if the alarm had stayed in so I really lucked out.