I purchased a '98 626 in April of 2004. I love this vehicle!

I have experieced a Check Engine Light message twice in the past 12 months. The first time was in winter, and I think it was truly the gas cap not being tight.

This past week, this light has gone on again and won't shut off...is it possible that becuase my daughter used "regular" fuel instead of mid-grade for 3 weeks while we were on vacation that there has been a problem?

MazdainGranton, Ontario Canada

 

Very unlikely that this is the cause. Regular fuel for your vehicle should be just fine. Check your owners manual for the recommend octane rating to use. Using a higher octane fuel does not provide any benefits other than to stop engine pinging. Light can be reset by removing the negative battery cable for a minute or two but is best to have the code checked to make sure it is not something important beginning to fail.