I had a Check Engine Light come on my 2007 Ram 2500 6.7L Cummins Turbo Diesel. Took it to the dealer, they checked it and found out that it was a code P2000. By looking it up I figured this had something to do with the O2 sensor or Nox filter. Either way, the dealer said they fixed it and all they did was just do a update the boot loader reflash and ECM reflash. I picked up the truck this afternoon, and to my surprise, the truck drives better than it ever drove since I owned it. They haven’t done any cleaning or anything like that… My question is does such a simple thing as an ECM or boot loader reflash make that much of a difference? It is pretty noticeable…. I am definitely not complaining, but just curious what made the change..