1999 Low Coolant Warning Light On

I drained and flushed the coolant on my 1999 Alero. Refilled with DEX-COOL coolant just as the manual specifies. Now the Low Coolant Warning Light on the dash is on! The coolant reservoir is full. I drove for about 15 mins and that did not help. I even disconnected the battery, no change. Any ideas???

When flushing the cooling system you need to make sure no air is in the system. Was it bled? Check out the coolant level sensor in the reservoir since that generates the low coolant warning light.