It's a function of the manual throttle control (left rear of the center console). Push the knob in all the way and see if it goes out. The light is there to remind you that the manual throttle is pulled out. The manual throttle is meant ONLY for static warm-up use, not a cruise control, since it will not disconnect when the brake pedal is depressed.
If you would like a copy of the Alfa Owners Manual, drop me a PM.
