Gas Cap - Check Engine Light

First, allow me to cut to the chase.

My Check Engine Light comes on and for a long while in the beginning it was most likely due to the Gas Cap.

Question: Would replacing the gas cap with one that’s not from Hyundai make a difference? Would using the one with a lock that costs a small bundle be better than one that goes for under $20?

I ask the above since I've replaced the cap with a generic one gotten at an Auto Store and it hasn't made a big difference.

The longer story:

My problems began well over a year ago with the Check Engine Light going off usually within a day after a fill-up. Not always, but when it did happen it was always after having done a fill-up. To which I followed a recommendation to tighten the gas cap and sure enough the light would go off within a day. Back then the folks at one shop checked all over but couldn’t find any leak.

That happened for about year. About 8 months ago I replaced the cap with one I picked up at an auto shop. Everything was fine for a while then the problem came back again. Mind you, I’d gotten one of those ‘Bluetooth OBD2 scan’ tools from a reputable company and the error code always shows Evap leak. Even took the car to a reputable shop and their test showed an Evap leak…so they checked all over and again nothing.
I’ve since would erase the code from the computer each figuring it must be the cap again.

Any suggestions would be greatly appreciated. Thanks.

Had the same problem about one year ago. Was told by Hyundai service manager that the car contains a computer program that checks the gas cap at a random time. If the cap is not in the correct position at a random time the check engine light will come on. The trick is to have a factory gas cap and turn until you hear one click after adding gas. The computer will look at a random time at the gas cap and shut the light off. I was told this is part of an air pollution law. I have a 2013 elantra. Nothing about this in the owners manual ,but it is a common problem.