Russell Kutach

Since this engine has louvers/dampers and can redirect coolant to different areas, I would also suspect the thermostat (if it has one) could be inop therefore causing the computer to get confused and causing the erratic shifts in temp. Im taking it into the dealer thursday so I will post what they find at that time.... dont want to kill my 60k investment.

Steve, im not sure how to check this...

I have 69k on my AT4 with 3.0 duramax and the engine temp started to rise erratically including all the way up to 260 degrees which is redline. This just started happening and I have never seen it get above 220 since it was new with zero miles on it. The trucks cabin heater is also working erratically and blows COLD air even when the engine temp goes up to 225-245. Its really cold right now with an arctic blast driving temps here in Houston down to 18 degrees so ambient is between 18 and 32 and this is still happening. I NEED cabin heat!!! I cannot swallow the fact that these engines like to run hot because this just started and the heater issue came along with the engine overheating issue all at the same time. anyone having the same problems??