2002 Corolla check engine light seems wrong

I have a 2002 Toyota Corolla. On a hot day (the first in a while), I got a check engine light for P0125. I'm going to clear it and see if it comes back. I think it is a false alarm for insufficient engine coolant. If the code and check engine light come back, what should I do?

Check your coolant to be sure there is enough and that there isn't any air in the system. If that's all good, that means the sensor is acting up and will need to be replaced.

How do I check if there is any air in the system?

How do I check if there is any air in the system?
Park your vehicle on a hill - nose up. Open the radiator cap and run your engine until it becomes hot and the thermostat opens. Air should escape and you should be good.

Good luck,
Sam