2000 PASSAT Check Engine light on

My check engine light came on 3 days ago and stays on. on the dash message thing its same EMISSIONS WORKSHOP. what does that mean?? My friend told me that she knew someone with a 2006 Jetta and that everytime she let her gas run to low the check engine light would come on and she'd have to take it in to get it reset. everytime they said it was because of the gas... any suggestions??