Check coolant level comes on right away after starting
 

my check coolant level comes on within 5 seconds of starting the vehicle. I was a little low on coolant once. I have noticed a smell that does smell like coolant and have noticed some white smoke after the engine has warmed up. 2000 dts northstar.

check engine compartment first for leaks

pressure test system

park on paper look for coolant if u notice none
run car for a bit and check paper again

Where is the white smoke? If in the exhaust you may have a blown head gasket