Cadillac Repair: Engine code 1258, gasket leaks, head bolts

Question
Working on a 1997 Caddy Deville Concours. Engine is getting hot then shutting down. I get engine code 1258 Which is Engine Meatal overheating protection. I have never seen this code before. Can you tell me what this means? Repairs made before it came to me were New water pump, and temp sensor...

Answer
This particular Cadillac engine has had problems with head gasket leaks for years and yet they do nothing to correct it. What is happening is that the steel head bolts are pulling loose the aluminum threads in the engine block and the only fix is to put steel inserts in the engine block, New head bolts and new head gaskets.