The message will pop up about every 13,000 to 15,000 miles.
It jst a reminder to check your antifreeze and make sure it's still good.

Darren gave you the details on how to check it. It is something you can wait till you get home, Not a immediate failure kind of message,

After checking it, you can reset the message int he command center by pressing and holding the OK button in the Coolant section. It will reset the internal clock for the next 15,000 miles.

The coolant is designed to last 105,000 miles under normal use and 60,000 miles under severe use. You can add the VC-12 additive to improve the corrision inhibitor ( 3rd test mentioned above) twice during the life of the coolant. It's about $14 a bottle. So I guess if you are on the average use schedule you would add the VC-12 around 35,000 and 70,000 miles and flush and refill at 105,000.

Just remember you have TWO coolant systems, They are independant of each other. So test both and add the VC-12 to both.