what needs to be done when my ESC light is on at all times while driving?
You have a fault detected in the Electronic Stability Control. You are safe to drive it but really should be addressed by a mechanic You can learn about ESC here: http://cars.about.com/od/thingsyouneedtoknow/a/ESC.htm
IIRC, the ESC light problem is the subject of a general recall by Hyundai; all original owners should have received a letter from Hyundai by now. If you didn't then call your dealer.
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