I would go thru the display and look in the memory for codes, write them down and then research what they mean.
Usually DEF injector or NOX sensor failure. Covered under emissions for 5yrs/3000hrs.
I agree with the above, pull codes and check and I also know DEF injectors can get blocked, or partially blocked and cause errors like this. I know this isn't exactly the same issue, but I'll add this just in case anyone else might care to read. This issue, sort of sounds like the issues I recently had with my diesel truck, and seems rather common on today's diesel trucks with DEF systems! Mine was on a RAM 6.7 Cummins. The DEF sensor over time built up corrosion from DEF fluid, a white crystal-like deal, where I had to replace the injector (mostly due to rust about eating away its mounts and hardware; living in a road salt belt has its cons). I have seen where some folks just remove the injector, clean it, and re-install; they're working again just fine afterward. So, not always having to buy new ones. There are tons of YouTube videos out there on cleaning these injectors if one wanted to look and see. If your machine has a DEF system, odds are it has a DEF injector - it would maybe be worth removing it, inspecting it, and cleaning it if needed. If it's not the injector, odds are, in my opinion, it might be the DEF pump, as that seems to be another common issue with diesel trucks showing this error. The injectors are typically cheaper than the pumps. Also, there are tons of aftermarket ones (made in China mostly) all over Amazon, eBay, and such, at way less than OEM ones, if one dared to use them! On a side note, the newer Peak brand DEF fluid in their platinum version claims to stop the crystallization build-up. From what I have seen in testing, it seems to be true. I switched to it after replacing my injector. Given how much DEF fluid I use, the added cost doesn't bother me, but everyone has to make that call. If it saves your injector and pump from build-up, it might be worth the added cost.