Check Engine light come on after oil change never done it before help needed

[toyota884runner]

Check Engine light come on after oil change never done it before. it came on right after i drove up a hill and stays on. the dipstick says it is fine oil wise. what could it be?? it's a 88 4 cylinder 22re 4runner. please reply

[KToy]

go to autozone or nearest parts supplier and have them hook up there diagnostic machine and that will tell you y the check engine light came on