P0711 KIA - Engine lost power, died overheated, radiator was blown, now code isn't reading at all. Can it reset itself?

Question

The Kia was going down the interstate, it has had problems with the radiator, there was a small hole, but we kept filling it with water when it leaked out. On the interstate it lost power and went from 70 to 45 then shut off and all the interior lights came on. It was smoking. It needed a little oil but not enough to warrant that kind of heat. The radiator was full and cool. After it sat for a while, we put the oil in and it drove home but had the Check Engine light on. Our mechanic read it the next day and said it was the transmission and it had gone into fail safe mode. On the way over to the transmission mechanic the car stalled out again, then finally made it. He said it was the engine when he read the sensor... now. Thinking the engine and or transmission are dead... we left it there and just tried to drive it home. No lights, no nothing and it ran fine except for the hole in the radiator. Is it possible that all the heat triggered something and all we have to do is replace the radiator?