Were you running and up to temp and getting heat when this happened, or did it go from a cold start?
Last time you checked your coolant level and freeze level protection?

 

Try blocking the radiator with something like cardboard. Block half of it. If it warms up you probably have a bad thermostat. Thats an easy fix.

 

 

The temperature gauge should indicate about 200° F when it's warmed up. The A/C compressor will not turn on when the outdoor temperature is below about 38° F. This is to prevent the evaporator from freezing up.

 

I just drove it again, and it was around 245 degrees most of the time. When I put the defrost on, it would go up even higher.
Might that mean I am low in coolant? When it got closest to 250 it gave me the error again that the engine was too hot so it was shutting the AC off.

I believe there is a little garage around here that is open Sunday. I hope. I’ll check the coolant when it’s light out, and then maybe take it somewhere if possible. Ugh. I have a 6 hour drive on Monday!!

 

I'd make sure you have enough coolant.if you have a kitchen thermometer it will work to show the temp of the coolant. 245 degrees is much too high.should at least 185 to 195 F ,not 245-250 F.,

 

I agree that 245 F is way too high, but the normal temp for a Gen IV 2011, is 210 F, higher than the Vortec engines from the 90’s. They will run at 210 regardless of the outside temp. It’s 5 F outside righ now, and my engine temp on my 6 liter 2008 was 210 F.

 

I put about a gallon or so of coolant in and now everything seems back to normal. We couldn't find any leak, so hopefully it's good. I'll get it pressure tested in a couple days. It's running right at 210 degrees.
Thanks for the input!!

 

Check the underneath side of the oil fill plug and see if it has any jellied oil on it. If it does, then it's got a leak into the internals of the engine.

FWIW my 2007 and 2010 both ran straight up at 200° F.