My car overheats! Is there a fix?

Yes. Replace your thermostat. Although you can use a cooler thermostat, this may not be a good idea. See this answer for why.

If this fails to solve the problem, you may be having difficulties with your coolant temperature sensor. This sensor also affects idle, air/fuel mixture, and timing, and failures can generally be detected by the ECU as error code #21. A burned out fan switch or relay may also be the fault.

For racers that run their car at sustained high RPMs, it is possible that their cooling pump may not be operating that well due to cavitation. For these people, an underdrive pulley will spin the cooling pump slower than typical, allowing it to operate properly. This is not a concern for non-racers.

If you have ECMLink, start the car with the rad cap off.

• Let the car get to up temp with rad cap off and watch ECMLink and the coolant at the thermostat housing. it should not be flowing.. just gurgling a little. If flowing. you have a stuck thermostat.
• Once the temps reaches 183-187... the thermostat should open and you should see temps dropping to below 180.
• When you see temps drop, looks at the coolant.. it should be flowing.  
• Once it drops below 180, coolant should stop flowing.
• *** If coolant is flowing all the time, you have a bad thermostat.
• At one point once the coolant has cycled from rad to block a few times at idle, the rad fans will come on as there is no airflow across the rad.
• *** If rad fans don't come on, you may have a bad temp sensor, fan relay or fan.