I've had my low coolant light constantly go on and off almost since I got the car. The Service Engine light even came on for a while. I had Autozone check it, and it said either the coolant was low, it had a bad sensor, or it had a bad thermostat. Well, it's got coolant, and I replaced the thermostat today. So, it's obviously got a bad sensor anyway.

Is that something someone with just basic mechanical knowledge could swap? And is it something I can just call me local GM dealer and buy?