I used the auto-shutoff at the gas pump but it malfunctioned resulting in a spewing fountain of gas out of the tank. After damage control, I started the car to leave and the Check Engine light is on now. Why? Is there a relationship between the two? There was no warning light on before the over fill.
Overfilling the tank can cause damage to the evap system. This system is designed to prevent gasoline fumes from escaping to the atmosphere. The system includes vacuum lines that run from the tank to the induction system with charcoal canisters and purge valves. When the tank is over filled, raw gas can be drawn though the evap system and cause problems. If the car is still under warranty, take it to the dealer, explain the circumstances, and let them figure out the problem with the CEL. If not, have your independant machanic look at it.
Fist step should be to get the codes read. This will pinpoint the source of the problem. It could be very minor, but get the codes read and evaluated first.
Busted is correct, some people do it intentionally trying to top off the tank. I will add that you may be lucky and by the time the tank is down to half or a quarter of a tank, it may have worked itself out and the evaporative system may be dried out. Good Luck.
We have two Chevrolet cars. I have packed the tanks on both may times and never got a check engine light. Go figure!