What causes 2009 hyundai Accents engine light go on after replacing the alternat

where are you buying the alternators? do you have the new/reman alternators tested before you leave with them? why is the check engine light on,we can't possibly know that. Take the car to a parts store,autozone,advance,oreilly will check that for free,then post the code(s) here for more info. there is no recall on your alternator although your original alternator failed at some point would not be out of the ordinary. now for the other 3,are they a good quality brand alternator?