Low coolant light on…constantly

A bad sensor?

My low coolant light goes on about one minute after starting the car. It almost does it when it comes to idle. Anyway I topped up the rad over flow to the proper line and checked the rad level, still on. I drive a bit check the level still the same, lights still on. I get home dump all the old water and put in new water, same thing. Any ideas how to get this thing off, it's more annoying than anything else. Could this be a sign of a bigger problem, such as thermo is going or water pump is going?

Thanks Scott

SonicMonkey opined in news: snipped-for-privacy@4ax.com:

Try overfilling by about 2 pints... if it stays on then, replace the sensor.

Late model? My 2000 has a plastic float that quit floating so I just tied it up.

I got sick of it, and just unplugged the sensor :)

I figure I'm under the hood often enough to check the coolant level. the idiot light doesn't really help. YMMV!