Most of the time the gas cap is loose, did not click shut, or has a worn rubber seal. The car tests its fuel vapor system for leaks, and an open cap looks like a big leak. Tighten the cap until it clicks. The light will not go off right away: the car has to pass its leak test again, which can take a few days of normal driving.
Your car keeps gasoline vapor in a sealed system, called EVAP, and burns it in the engine instead of letting it into the air. Every so often the computer seals that system and checks that it holds. A loose cap, a cracked seal or a cap that does not fit lets air in, the test fails, and the light comes on.
It is a pollution warning, not an engine problem. The car drives exactly the same.
P0457 is the clearest: some makers use it for a loose or missing cap. P0455 is a large leak, which is often the cap too. P0442 and P0456 are small and very small leaks. Those point less to the cap and more to a cracked hose or a valve.
If the light comes back with the cap clicked, or the code is P0440, P0441 or P0446, the problem is elsewhere in the system: the purge valve, the vent valve, a cracked hose or the charcoal canister that holds the vapor. It is still not urgent, but it is worth a shop visit.
One habit that causes these: topping off after the pump clicks off. The extra fuel can soak the charcoal canister. Stop at the first click.
If the light came on right after a fill up and the car also runs rough, hesitates or stalls, bad fuel or water in the fuel can cause misfires. That shows up as a different code, in the P0300 range, and should be checked soon.
Usually a few days of normal driving. The car has to pass its leak test again, and on many cars that test only runs after the car sits overnight. If it is still on after about a week, have the code read again.
Yes. A loose cap does not hurt the engine. Click it shut and keep driving normally. If the light starts flashing, that is a different problem and more serious.
You can, with an adapter and the app. But if the leak is still there the light comes back, and clearing resets the emissions monitors, which can make the car fail an inspection for a while.
Estimates only. A mechanic should confirm. If the car shows a hot temperature gauge, an oil pressure warning, smoke or a burning smell, stop as soon as it is safe.