I was accelerating onto the interstate when all of a sudden the car started running real rough and gray smoke started coming out the exhaust. My check engine light started flashing, then stayed on all the time and I got a "reduced power in the engine" message on my instrument panel.

Took it to a mechanic, who read the codes and said that the #6 fuel injector was stuck open, causing gas to pour into the engine. He needed to replace the injector and switch out the coil pack. Also, since a bunch of gas got into the oil system, an oil change needed to be done, too. By the time it was done, it was about $700.