Sunfire overheating

is the coolant full and fan coming on ?

did you allow for the coolant to purge when filling?

Only other things to check are the coolant flow through the radiator, engine block, heater core, and hoses. The radiator cap should also be checked for its pressure relief function.

As bad or faulty catalytic converter, which can disrupt the normal combustion properties of an engine, can force the engine to work harder in order to emit the burned exhaust gases, or exhaust. This raises the operating temperature of an engine, and if left untreated, can definitely cause a car's engine to overheat.