[shakewell]

The shop would've cleared the code after they fixed it.

About the original problem - when the person scanned and found your code P0440, did he clear it or just send you on your way. If he didn't clear it, it might be a one time thing where you filled the fuel with the engine running or something like that.

I would clear the code, then drive it until it comes back on. When it does, scan it, make sure it's the same code, then start with the gas cap.