Evaporative emission control system leak detected (gross leak) can someone give me some advice as to where to start looking? 2007 Avalanche
Gas Cap On Tight?
Make sure it’s clean around the neck and the cap. Caps are relatively cheap.
Out of warranty, already?
CSA
Try a smoke test. It’s a test where smoke is pumped into the vacant areas of the fuel system and blows out the leak.
You could possibly have some chance for warranty here as these systems must work for 2 years regardless of mileage. Why are you out of warranty?