Coolant Light-- 2001 Volkswagen Jetta 1,8T?

Easiest way is open the hood and look in the overflow reservoir and check the level when engine is cold. Like the first thing in the morning. It has a hot line and a cold line.. Maybe you have nothing in there so add some would be a good idea. You own the car. It is yours to take care of. Before the car existed it was a horse. If the carriage did not move maybe it is because you forgot to check to see if your horse is alive. Car is no different except you have more things to check. Most are visual checks and that is why God gave you eyes. I can't see from here.

It is either a sensor or low coolant. Pretty much guaranteed to be one of the two. It could also be the system checking itself. You did say it doesnt stay on. Previous poster is correct, if it is low you can pour it in the expansion tank. (Green coolant, FYI.) This is a lot like the system on my 1986 BMW, there would be lights forward of sunroof, and if they are all off all is good. Sometimes they come on due to bad sensor and all was OK. 2001 Volkswagen Jetta is one of the 'Unloved' years, but its a nice sporty little car. I love Jettas. They had groing pains A4/mh4 model, like yours, but they are fine.