1995 Ford Contour Check Engine light coming on and off

Hello and thanks for helping this damsel in distress. I've had NO trouble with my car despite it's age and the past two days, the check engine light has come on and gone off after less than a minute in each case. The manual says if the light goes off, the engine has returned to normal. However, the light has never come on before, so before I take it in to an unknown mechanic, I'd like to get some advice about what to do.
Many thanks!
Donna