took to advance auto and they tested emission and found #p0456 evap emission control system leak very small.Call gm and they didnt give a locationfor sensor,can anyone help with this problem. Thanks

 

I can tell you that not long after I got mine (used) I had to get the gas cap seal replaced. It wasn't sealing correctly and that was causing the service light to turn on. Don't call GM, you won't get anywhere. Bring it in to your local dealership and they should be able to take care of it for you (even if your problem is different). The aveo seems to have quite a few problems that trigger the service light.