Go to your local auto zone or parts store (checkers) they will plug into your car and tell you why the light is on before you should clear the code. Most are on now for gas tank pressure. Try tighting your gas cap intill it clicks. Be sure to get the code before trying to clear the light. If you want the light to go off remove the hazard fuse/ecm fuse (under hood fuse box) for 30 seconds and that should clear the light. If if comes on agian then you have a problem, and it needs to be corrected, or possible damage to the cat will happen.