check engine light
Yes, "dumping the codes" is slang for plugging a code reader into your vehicle's computer to determine what the error message is stemming from. If you've somehow already determined that the message is due to the fuel cap not being on tight enough, that is a common code, which in time goes away without incident. I've found that when I occasionally top up my gas tank the car doesn't like that and it will result in that error code popping up. I can usually just clear the code and it won't come back. Or, if I don't do anything and just drive normally for a couple of days, it will go away on its own.
I grew up in Summerland, B.C., so I know exactly where you are located. If indeed your error code is the gas cap one (I forget what it is called exactly), you needn't be too worried, and making the drive from Kelowna to Vancouver should not be a problem. However, if you haven't pulled/dumped the codes and don't know for sure why the check engine light is on, you should do that first to be certain another more ominous problem isn't lurking, waiting to stall you along the way.
Good luck, and watch out for that Ogopogo as you're driving through the Okanogan Valley!!
Rob







