2019 Newmar Ventana Problems

On 5/23 I started getting a code "SPN3031 FMI9" which says the DEF temperature is rising too fast, no other codes were present in the fault list (the engine was running at the time I grabbed the fault list). Only the engine outline icon was lit. I had only driven 3 miles from my house to fill up the RV with fuel. I turned the engine off and restarted, getting the same code. After driving back home I pulled up the list again and it was the same. On 5/25 I contacted the local repair shop and they took my information. They called back on 5/26 saying that Spartan (chassis manufacturer) thought I should have more codes. Early on 5/27 I pulled the fault list from the RV with the key in accessory position and I got 2 fault codes, the SPN3031 and also a "SPN1761 FMI9" but it also showed different icons than the prior query, also showing the "check engine" and "Regen" lights. Since I had seen 2 different fault sets I decided to remove the key and try again. I only got the single engine outline icon and the SPN3031 code. I didn't receive the SPN1761. I provided this information to the repair shop shortly after they opened and about an hour later I got a call back from Spartan. They indicated that I would need a new DEF head, the one I had was failing and it was a very common problem this year such that they had none in stock. They also said they weren't sure when they could get me a new one or how many miles the RV could be driven before it would start to derate it's power. I fully support the DEF improvement in air quality, but it is not safe to have a vehicle that is going to start derating power potentially leaving it useless and no ability to get the warranty replacement parts quickly. Manufacturers should have to supply parts for warranty claims before they can sell new items when there is a shortage. The consumer shouldn't be left with an inoperable vehicle while they sell the limited supply to new consumers for a profit.