Some engine lights are because of X number of anomalies per million cycles.
Don;t forget that the devil's brew they call gasoline nowadays can cause trouble with fuel systems. Without knowing what's been done to the car, how you drive, and what the dealer service techs have done to check the trouble out, I can't guess as to the nature of the problem
But as suggested, I would take the car to another dealer. if the problem persists, demand to speak to the region manager and tell him it's his job to make your car right
There will always be a certain number of cars with problems, no matter how good or bad the reputation of the manuafacturer. General Motors is a car maker with good quality now. This isn't the 1980s, anymore, Samguy
For example, GM's Buick division is now tied for 1st place in Quality, with Acura. Honda, Mitsubishi, Kia, Mercedes, etc, are inferior makes to part of GM right now in terms of quality. Buick is making better quality cars than Honda. I know it's difficult to understand
Since GM runs as a Corporate maker nowadays, and not as individual divisions, you can expect the rest of GM to have pretty good quality as well
This engine light of yours can be many things. I just recently had a similar problem with a GM, and it was an check engine light that was "fixed" three times. There was a bad wire, that somehow got rubbed and damaged.
The trouble is that the computer diagnosics won't pick that up all the time, they had to look at it a number of times before a tech spotted the torn wire. It was nobody's "fault" but it was frustrating