Coolant sensor

My low coolant light is on but I have more than enough coolant in the overflow. I tried cleaning the sensor but it didnt work. I can disconnect for now. The car has been sitting all winter and there was a drop of antifreeze but I am 99.9% sure that was from overfililing it.

Is there any other possibilities for this light stuck on other than a bad sensor? Can they be replaced without replacing the whole cap assembly?

Thanks
 
The low coolant level sensor isn't monitored by the computer. If it malfunctions, the only thing it really does is annoy you. You can take out the bulb if you don't want to try to troubleshoot it. Mine hasn't worked properly for years, and it hasn't been a problem.