This happened after I was dealing with intermittent AC issues that would involve AC not cooling and a check engine signal that lit. After turning off the engine, I could hear the motor running briefly once it stopped and engine turned back. AC would be fine and no CE light. It was thought that it was a sensor issue with the AC. We maintain the car regularly as we have over 175,000 miles. After 2 trips to the mechanic (Firestone first then GMC for second opinion) there were no problems found with the AC or engine.

For a new air filter Freon. Problem seemed to persist intermittently every few days. Then within 3 weeks of having it checked we were driving home on the Interstate no AC issues no engine nor any other warning lights but suddenly the CE light came on but this time it was flashing, then suddenly a loss traction control signal. The car begin slowing losing power and we had to pull over immediately. We were traveling I-10 over a large spillway in Louisiana so we were stranded over a large body of water waiting for roadside assistance with our children. Turn out to be total engine failure.

I am far from mechanically inclined and understanding - it appeared to be a water pump suddenly exploded, where fluid spilled and damaged the engine. Not sure if this was what was causing the AC issue or ransoms CE light. GMC dealer recommend wngine replacement $4500 for engine with $4000 labor. Whole situation sucks due to still paying on the vehicle I purchased used 3 years ago.