I had this same problem last week. Message came up and said that the wrong DEF fluid was detected and my truck would be disabled in 200 miles if I didn't take it to the dealer. It was the same DEF I've been putting in for a year and a half. I called the dealer and made an appointment. As I was on the phone, the code went away. I wasn't taking the chance that my truck would be "disabled", so I took it to the dealer. They said it would be $90 just to hook it up to the diagnostics. I told them I wasn't going to pay it, and that I just wanted my truck to be able to run. They said they have to hook it up to find out what's wrong. I told them there's NOTHING wrong with my truck! Long story short, the diesel tech came out and reset the code. I asked him, could I have just done that with my code reader at home? "Oh yeah, sure" he said.
Lesson learned. I went home and did some research. That's when I found out I could get a Green Diesel Engineering Hot Tune and delete all the emissions BS (DPF, DEF, EGR) they put on the truck and get better performance and fuel economy. I emailed GDE. GDE was shut down over three months ago by the EPA, but they did send this:
We are not able to reflash/install our tune at this time due to changes in EPA rules. Best to contact your state representative and ask them to reign in the EPA if you ever want the GDE tune. The EPA is using statute CAA 42 USC 7522 (a)(3) (A-B) to go after the after-market auto industry. We feel this rule should only cover large auto manufacturers, not older vehicles in the field.
There is an act in Congress called the
RPM Act that is on the table. Please refer to below if you contact your representatives and ask them to move quickly on this bill:
https://www.congress.gov/bill/116th-congress/senate-bill/2602/text
So now I'm wondering, If I iinstall a straight pipe exhaust on my truck it'll bypass all the emissions crap. However, I'm sure it will trip codes. If I can reset the codes myself, I should be OK. I'll just have to stop every 200 miles and reset them. I'm old, so I stop to pee that often anyway. I might just he stubborn enough to do it.