Wife's car wouldn't take gas... This "thing" appears to be a rubber valve of sorts behind the metal flap that moves out of the way when you insert a gas nozzle...
Seems attached to something anyway, didn't have long and thin enough pliers to attempt extraction. I pushed it in and filled up OK... No OBD trigger (yet) as the gas cap is still sealing all this...
You guys even seen something like that ? I wonder if it would be covered under "emissions" by manufacturers... 8y old car....