Hyundai Repair: Emissions Malfunction indicator light., malfunction indicator light, hyundai elantra

Question
I have a 2001 Hyundai Elantra and I lost the gas cap and did not know it (forgot to replace during purchase).  During this time the malfunction indicator light (I call the check engine light) came on.  I then realized about the fuel cap and I replaced it. The light is still on does in need to be reset and/or is this the possbile cause of the engine light coming on.  

Answer
Usually, the lamp will go out on its own in about a week or so.  You can reset the lamp and clear the codes by disconnecting the battery for five seconds.  If the check engine lamp doesn't reilluminate, it's a reasonable conclusion that replacing the fuel cap solved the problem.