1996 Saturn Station Wagon possible EGR valve problem

Check engine light came on. Service tech determined code reflected faulty EGR valve. Replaced valve. Light went out. Coupie weeks later light came on again. Brought in, faulty valve again replaced. At annual inspection light was on again passed inspection, no light. Few days later light on again. Not sure tech has solved problem. Light came on again. Not sure where to have it analyzed. Can you shed some light on problem. These incidents occurred between 88000 and 90000 miles over a two year period. Don't drive it very often.