We bought a brand fresh out of the factory 2011 Optima, which had to be returned to the dealership after 500miles for the engine light.
The service department said that the car had a faulty gas cap and make sure that we DO NOT top off at the gas pump.
200miles after the engine light was reset it came back on again.
This car has been into the dealership 5times for the engine light, each time the service dept says it is a vapor leak!!
If a car has been returned 5times for the same issue, apparently there is a real problem and just turning off the engine light DOES NOT fix the problem.
The gas mileage greatly suffers when the Engine light is on.
After having to take it to another KIA dealership they found that the engine light code showed that the PURGE VALVE SENSOR failed in the car.