it'll come back almost all the time. save the hassle and get a code reader, even a cheap one and google to reference it will do.
i keep my code reader in my trunk. that way if i ever get a check engine light on the road, i can pull over and check it out. in seconds i know if its a problem i can easily get home on (or longer) or if i need to get the car off the road asap. for example, i'll fix an o2 sensor or an evap problem when i get around to it. bunch of hard misfires, not so much.