Gas cap
The seal can age enough over time to cause a check engine light because it doesn’t seal properly. Aftermarket caps don’t vent properly and the locking ones don’t seal right (again, the check engine light).
These are Toyota genuine parts so you know they will do all of the things that they are supposed to.
Quit using that cap you found on top of the gas pump and get the real thing.
**seal only fits the type that doesn’t have a lanyard, the others are CAP assembly only.