I have a 2000 Dodge 2500 with the 5.9 gas engine. I have had this truck for over 10 years, it had around 45,000 miles on it when I got it and is at 155,000 miles now. None of the wiring has been jacked up in any way. I started having a P0446 code, which is purge valve wiring fault, the purge solenoid was replaced at the shop, it was already there for tires and they checked the code. The fuel pump had just been replaced by me a couple weeks earlier. The code still persisted, and it started quitting all of a sudden, with the NAobus message on the dash, mostly after sitting idling, for say 10 minutes when it was hot outside. I checked all of the pcm connectors and pins, they looked great, I can’t find any wires that have rubbed anywhere. I decided to try a new pcm. With the new one I no longer had the p0446 code, but still have a problem with it going dead and the NOBUS message. It does not seem to be as frequent as it was with the orginal pcm, but is still a problem. I’m stumped and any help is appreciated.

 

The PCM is going MIA, "nobus" means the cluster isn't receiving messages from it. Could be power to the PCM, ground for the PCM (not uncommon in the rust belt) or in some instances a short in the 5V sensor supply takes down the whole PCM. As it appears to be temperature related I'd guess a bad connection is heating up.