Any time the check engine light comes on you should worry about it. If it gives you an O2 code, which is the most common, hten you need to replace the O2 sensors. If you don't the car will run rich and eventually destroy the cat. causing a rotten egg smell and blocking you exhaust. Either follow the links given above, the info Jorge posted from Julian's site or use the 'SCPOC' link in my signature. All of them will tell you how to pull the codes and what they are for the 93-95 cars.