Check engine light on

Are you sure that you screwed the fuel cap on tight? That can trigger a check engine light.

Also drove 100 miles then stopped for 3 days while camping. Three days later started the engine and light still was on. Came home unloaded the camper light goes out.

Thats strange, usually when the check engine light comes on the Duramax engine goes into a limp mode and you can move, but barely. Your top speed is restricted to about 10 mph. I would keep the appt.

...check engine light can be a ton or reasons...very few trigger limp.
I had one that turned out to be #8 glow plug. Drove another 3 days towing..with lots of shut downs and start ups...no limp.

Glow plug and glow plug control module replaced under warranty.

Thats strange, usually when the check engine light comes on the Duramax engine goes into a limp mode and you can move, but barely. Your top speed is restricted to about 10 mph. I would keep the appt.

Thanks for suggestion. Camper was on the truck for 5 month no problem. Light came on after I got fuel. Drove another 100 miles with light on and no problem. Decide to take to dealer so I took the camper off. Light went out.

Try to recreate the conditions...Put the camper back on. They will run a scan to determine what code it is throwing.
Could be anything as simple as a loose fuel cap to a glow plug issue or injectors.
Good luck with it.

Keep the appointment. Last thing you want is a mechanical failure in the middle of nowhere. However, with your TC on board, you always have a bed available! :)

The Check Engine light could be a zillion different things. And with the computerized systems, the way they are, it's nearly impossible to figure out what could be wrong. Better to get it check-out and have a very minor bill, than wait for it to go "ka-put!" and end up with a gigantic bill!

I would plug the camper back in without putting on the truck. If the light comes back, then you know it is a camper wiring problem.
If you put it on and the light comes on, go by an Oreilly's or Autozone and have them read the code.
Dealers will not find anything and charge for not doing anything.

I would put the TC back on, and keep the appt. It may help them troubleshoot the problem. It sounds as though the trailer/TC wiring has issues.

Wayne