High idle while driving?

[timberland]

I just purchased a '16 GMC Sierra Denali 2500 Dmax . On a return trip driving about 60mph coming to a stop on a back road I noticed the idle was about 950 rpms. Truck has 1300 miles on it now. No codes, no high temps, not pulling any trailers or box campers. I stopped to fill up with fuel and upon restart the truck idles down normally 650 rpm(?) ...definitely lower than it was while driving. Why the high idle?? My 02' or 06 Dmax never did this.

Another....seems the cooling fan runs a lot with this truck compared to my previous owned '02 and '06 model. This '16 seems to run a bit on the warm side too. Guessing emissions and the EPA had something to do with the temp increase ???

Personally I would like to truck to run a bit cooler.

Thoughts suggestions on these new '16's ?? Mileage is back up to what my 02 got running 78mph with this '16 ( about 20 mpg ). The 06' sucked fuel ( about 17-18 mpg )...but it ran 138,000 trouble free miles.

[cabletech]

The idle speed will be higher if it's in regen. When you restart the truck it doesn't go right back into regen so your idle speed would be normal.

Jay

[Kennedy]

With the emissions system on these trucks running a DPF I believe it is important that you monitor this function. It is meant to be seamless in operation and give you very little clue as to the mode, BUT it also lacks enough diagnosis to measure proper operation and success.