1999 expedition is smoking grey smoke

:rolleyes: my ford has 120k and grey smoke started to come from the exaust and the service engine light came on why is this can someone help please

they are charging me 630 dollars for a gas cap for cleanning my fuel injector and some ECP celunoid plus cleanning corrosion from my battery and some valve that was open.....is this a correct price

Is there anyway you can get the codes posted for us? If the check engine light is on, there is a code stored. We need the exact code number. As a guess from the little info would be the EVAP solenoid. If she can get to an auto parts store, have them plug in their scanner and post the exact code number for us. Thanks.