Some questions - none need to be answered just things to think about...did you recently get gas and "top off" the tank by adding gas after the first shutoff. This can cause sensors in the fill neck and the charcoal canister to report odd things. Along the gas line thinking, did you get gas at a place different that your normal fuel location - i.e. could it be that you got bad gas (this happened to my wife on a long trip) as this can trip various sensors. Check all your fluid levels - wife's car threw emission codes when her coolant level was really low. With my wife's car issues, fixing the real problem (adding fluid to radiator and putting in fresh gas) caused the CEL to turn off and not come back.