06 3500 crew cab LB single rear wheel. I have had the check engine light turn on 3 times when climbing a hill. This last time it did it and I was not hauling anything. I do not have gauges. My mods are 7" lift 36"tires hypertech programmer set at level 3. 4"exhaust cat back system. My questions are: Can the light come on when the egt's are getting hot? Does the truck have a way to monitor it's self? I live in Vegas, when ever I am coming home from L.A there is a town called Baker. As you jump on the 15N passing Baker you start a 4,000 ft climb. I shift my truck in Mann.mode 4-5th gear never passing 2,300 rpm. Tranny temp normal,engine temp normal.The reason for this is that the Allison on the 06 comes with 6 gears. 6th for this climb is a little weak. Since I have this lift running stock gears I need the extra rpm of a lower gear. Speed 70-80 mph when not hauling. 55-65 mph when pulling trailer. It never fails check engine light comes on! 2-3 days later it goes off. Why!!!!! Has anyone had this happend? Is there something I need to do or install?:eek:

I'm not sure if the cel and the egts are related, sounds like they could be.
I would suggest getting at least a pyro to monitor things a little better.
You might get a better idea what is going on then.

i had a prob with the check engine light also 1 sat night driving around the check engine light came on and the truck drove like crap, would no shift right, the next day the the truck drove fine and the check engin light was on for about 10 miles then the light went away, yesterday almost the same thing happened again pulled out of my driveway headed down the street and the light comes on again, so i went back home and took the 6 gun off, took to the dealer and they checked it, they told me it was bring up a funny code and could not get rid of it so the had to reflash the computer,

I would suggest the problem is the EGR...There have been a number of folks on here with the same, almost word for word, problem...They took the vehicle in and the stealer does an ECM re-set for the EGR and all is well...

http://www.dieselplace.com/forum/showthread.php?t=151095

Agreed with other posts on here, sounds very familiar with their problem and ended up being the EGR, go get it reflashed, and get some gauges, that is one thing I am gonna do.

07 max I saw you gave the same advice to another guy asking the same thing. Is this common with this these trucks? Do I go to the dealer and ask for this? I will be pulling the toys to Dumont this week end, I guess I will see if it does it again. This time I will do 50 mph up the climb to see if it does it again.

Do you guys think that this can be happening cause I am running the stock air box and a cat back system? Not enough cold air and to much restriction from the catelitic?