WM75Guy
Elite Member
With my GMC pickups the only speed restrictions are when you run them out of DEF. The auto regen function works great. It is supposed to happen once every tank of fuel. The regen light only comes on when the truck hasn't been driven long enough or fast enough to let the regen process happen. When the light comes on you have to drive at highway speed for 30 minutes to allow regen to occur. It doesn't limit speed. I have never seen the light come on and I am on my 3rd GMC Duramax with emission systems.