u/Hootyhooneedsaboo

Hello everyone. My girlfriend bought this car a few months ago. We’ve had a constant check engine light and haven’t had the money to take it into a shop. The guy we bought the car from gave us a new gas cap hoping it would fix it but to no avail. Is this gap a possible issue or is it supposed to be a sealed system past this? All the codes its pulled have been the ones that say theres air in the system or a leak somewhere in the fuel system. Also yes the gas cap has been put on tightly with a click every time.