engine lite/ oil lite on

I have a 2005 turbo pt cruiser convert. 64000kmThe engine lite came on and stays on. It was diagnosed on a machine as a vapour leak. Was told it is hard to find wait until it gets worse...meaning,,,,, Changed the gas cap no change.
Now my oil lites comes on once in awhile. I shut off the car and it goes out.- usually when the weather is cold.