I have a 1996 cadillac deville with a 4.6l northstar and have a P1258 code how do i fix this

Question

P0141,P0138,P0741,P1139,P1258

Answer 1

P1258 Engine over temperature protection

P0138 H02S circuit high voltage Bank 1 Sensor 2

P0741 TCC system stuck off

P1139 Insufficient switching Bank 1 Sensor 2

To resolve P1258 you would really need to be sure that the engine is not overheating. or low on coolant or water level, just filling up the radiator is  still not enough, you need to purge air that is trapped in the cooling system either bleed the air out by opening up a heater hose , or the upper radiator hose and ensure there is no trapped air in the cooling system