Honda Civic VTEC and dashboard engine check light staying on

I have a 1994 Honda Civic EX-4 door with 300,000 miles. This is my second question today.



I took my car to the Honda Dealer in 2006, and they checked the computer, which reported that my VTEC system is bad or a least a component within this system. They said that the VTEC kicks in when I drive a high speeds (over 70 miles per hour). What is the purpose of the VTEC system? How can I get the engine light to turn off. Sometimes while the car is cold the light stays off. How can I fix the VTEC and is there any dangers of driving with this condition?



Thanks for your responses.