This car has been awesome until Oct then it over heated, so I flushed the radiator, changed the thermostat, and water pump, replaced bottom hose on radiator, now the car runs good for a little while then, the inside air goes cold, check engine light comes on gives a code of P1285 cylinder head too hot, but the tempo gauge doesn't always go up, if the temp gauge goes up, the check engine light usually doesn't come on, my brother in law wants to replace the cylinder head temp sensor and the blend door actuator, but I'm not sure what I should do..anybody help me??????