On most cars and trucks now all you have to dod id trun the key one and off and back on real fast and a code will so up/. Look that code up. My 2001 Dodge Dakota light came on. last week. Number 4 spark plug mis-fire. A ver common check enigne light trip is a loose gas cap. Yes, if the gas cap is loose it will trip the check engine light. By the way the one on my truck resets by it self after a day or so if nothing else trips it again.