Son has a 1997 contour with 2.0l overheated

I would want to check coolant flow into the radiator, if possible. Does your radiator have a cap, can you stick your finger way down in the coolant, cold engine. Some cross-flow radiators you can drain the coolant down far enough to see the top two coolant passages. Then with thermostat removed and everything hooked up, the coolant flow is instant, when you crank it. Sometimes I do this just for testing. If no coolant flow, have to check water pump and belt. I can't tell from here if there might be blockages in the engine coolant passages?

Clear the code and drive the vehicle. If the code comes back, then you know it's real condition and not a one time event.
Changing the temperature sensor isn't going to remedy the situation. Most likely the thermostat will need to be replaced.

The radiator could be plugged up from corrosion, due to age.

If your not low, and your not overheating, chances are that the level sensor is either dirty, or faulty. It's located in the coolant resevoir.

Temp sensor or air pocket near the temp sensor. replace the temp sensor and follow correct fill procedures for the coolant.

The sensor would not likely have shorted, but the sensing material may have changed due to overheating. The thermostat may also be in trouble. Replace both, then take the car to Autozone or similar business for a free computer scan, which can remove any error codes. Then drive the car to see if it resets further codes. Make sure the cooling system is topped up in both the radiator and the overflow tank. Check your other hoses for condition and replace if necessary. If the entire engine overheated, be on the lookout for antifreeze leaks around the heads and for strange misfire codes. It may have warped the heads from excess heat. Hope this helps!

your thermostatic fan relays aren`t funtioning properly

Does not run at all time, depending coolant temp, did you check the coolant level ? You may have a faulty thermostat or plugged radiator.

Sensor will be around the thermostat housing Follow the radiator hoses back usually the top one