Coolant light comes on

I have had my 1998 Chevy Malibu LS since February of last year. Now the coolant light comes on and soes out after 3 to 4 minutes. I have heard people say that something like this could be a bad gasket, then another tell me it could be my sensor. Does any one know?

if your coolant is low, it's a leaky intake gasket. If the coolant isn't low, its the sensor.