sorry it took so long to respond. I wanted to let you all know that for now, the problem seems to have gone away. It didn't seem low on coolant, but I added some anyway and the light hasn't come on since.

By the way, my friend replaced 2 coolant temperature sensors. They are located right next to each other near the thermostat housing. One has a black plastic 2-prong connector, and the other has a copper 1-prong connector. Or something like that...

Keeping my fingers crossed, wish me luck and thanks again!!!