Hyundai Repair: Check engine light and loud noise, hyundai accent, accent 4

Question
I have a 2003 2-door hatch-back Hyundai Accent, 4 cylinder, automatic. The check engine came on about a month ago, but went away 2 weeks later. Now it is on again and yesterday and today it sounds loud when I start it, when it idles, and when I accelerate. recently I have also noticed a slight rattling sound. Any ideas about what this could be? I do not know what the check engine light code is, I have not brought it in to get checked out yet. Thank you!

Answer
I'm going to guess you have an exhaust leak as this can both cause loud noise and a check engine lamp, but they could simply be coincidental.  For proper diagnosis, you'll need to investigate the noise and check the diagnostic trouble codes.  Without hearing the noise, it's difficult for me to determine the likely causes.  Without the diagnostic trouble code, I do not know the nature of the problem that caused the check engine lamp.