Is the code for the check engine list the same every time? (probably not if they are throwing sensors at it).

But here we have an incompetent dealership and you are blaming the car. If the car was not fixed the FIRST time, ( i don't know how much time you have between visits light coming back on) but most GOOD reputable dealerships would fix it right the second time, this is what i just said "not every gm mechanic can fix the aveo" its a daewoo.

I'm not attacking you for blaming the car, the dealership probably even has you believing its the cars fault and not them, while carefully approaching their repair behind the scenes so its not a lemon (i've been there) but this is definitely the dealers fault for not being able to service you. I am guessing you are now out of the 36k 3 year warranty? It should entitle you to a loaner car if you are still in it.. I got one when my fuel pump died, it was a cobalt, i hated it.