what causes the check engine light to stay on on 2006 Chevrolet Tahoe

I called onstar and they ran a diagonistic and said service the fuel system is that like changing out fuel filter or is it more

Asked by for the 2006 Chevrolet Tahoe
did they tell you the exact code?and yes there i'd say there is more to it than just changing fuel filter. they were probably just referring that it was a code flagging a fuel system malfunction.