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, but, I'll add this just in case anyone else might care to read?
but this issue, sort of sounds like the issues I recently had with my diesel truck, ?? and seem 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 slat belt has its con's for sure)
I have seen where some folks just remove the injector and clean them and re install, and there working again just fine afterwards
so, not always having to buy new one's, when issue happens9I'm sure a dealer will tell you have to replace, if under warranty, NO biggie maybe, but if not, cleaning might save a few bucks)
ton's of you tube videos out there on cleaning these injectors if oen wanted to look and see one)
if your machine(sorry I don;'t know for sure)
but if it has a DEF system, oddsd are it has a DEF injector,
I would maybe be worth removing it and inspecting it/cleaning it if needed!
if its not the injector, odds are IMO< its the DEF pump, or that seems to be the #2 issues in diesel trucks with this error!
As they too seem to over time get same issues with built up causing failures
the Injectors are cheaper typically from what I gather than the pumps too! But also seem now, there are tons of aftermarket ones (made in China mostly) all over amazon, Ebay and such, at way less than OEM one's, if one dared to use them!
and on a side note,
the NEW or some what new, Peak , brand def fluid in there platinum version, , is supposed to STOP the crystallization /build up on things, or so it claims and from what I seem on testing, it seems to be true?
I switched to it after having my injector replaced, , for how much of it I only use, the added costs don't bother me, but everyone has to make this call!
but if it saves your injector and pump from build up, it might be again worth the added costs!