I got this CEL code P0440. The light turned on right after I started my car, The car was still warm. The light was on for only a few minutes before turning back off.
Scanned the car the next day, Got this code. Found out that the common problem for this code is the gas cap being lose. In this case mine was not. I just got back from kodiak, and my wife says the light came back on for a few minutes and turned off again, Scanned the car and got the same code.

So what should I do/look for to cure this problem?

Gas cap is fine/never had a problem with it.

The code states: Evaporative Emission System. Which I do not know anything about so any suggestion would be awesome.

Let me know if you need any more info.

Thanks.