Check engine light is on. I replaced the gas cap but the light didn’t go off
What code(s) are you getting?
You really need to know the specific code. There are hundreds of them and a new gas cap will not be the answer to all of them.
Take the car to a local auto parts store like Advance, Autozone etc. They will read the codes for free (unless you are in California) Post the codes here they will look like P1234