Is this the crankcase vent recirculation hose? If you mess around with installing aftermarket intakes or air filters, you can break it. I did. Superglued it back onto the intake elbow and have been more careful with it since. Has held up fine in the year since.
If your gas tank cap is not sealing because it is missing the seal or because you have not tightened it until it clicks, you can get a similar code since unexpected air will be introduced the system.