If you've ever seen a car driving down the street with steam coming from under the hood, then this light has probably been on in that car for a while. It means your car's temperature is too high, and if you keep driving with it on, your car will eventually overheat.
If it comes on in your car, you need to pull over and turn your engine off as soon as possible. Until you are able to do that, you should turn your car's heater on the highest setting, as this will remove some of the heat from the engine (and blow it on you).
Common causes of an overheating car are:
- Low coolant
- Electric cooling fan failure (bad electric fan or bad radiator fan switch)
- Thermostat not opening
- Broken fan belt
- Clogged radiator