Well, it sounds like the radiator light.

That means you probably wanna check your radiator. Let the car cool down, and open up the cap on the thermostat, if it needs water, put some in.

Open the cap on the radiator overflow bottle (white bottle to the passenger side of the radiator) and make sure there is water in there.

-Jesse

I went and bought some antifreeze, and filled up the overflow bottle, but didnt open the thermostat. I guess I will check it out, and you say just fill it with water???

Well, 50/50 antifreeze water mix would be the best. But I just said water. If it's just in the thermostat, to top it off, just water is okay. It's not going to dilute the rest of it enough. I'm sure you could add straight antifreeze too. Just as long as it's not too much. You want to try to keep that 50/50 (or so) mix of antifreeze and water. And since the total volume is something like 2 gallons I think, if you add straight of one thing or the other, it won't affect the mix too much.

-Jesse

What should I do if that doesnt make the light go off?

Your sensor may be disconnected or malfunctioning. My 300XZ blew the top of the radiator a few years ago and I had it replaced by a local shop. later, when I had the car back in a Nissan house they insisted that my radiator was bad, they were saying it had a pressure leak. It took me 30 minutes to explain that it had been replaced, but the ECU hadn't been reset...maybe a similar problem for you?

I dunno, it came on when I was on the interstate. But, its running fine, I will reset the ECU and see what happens.