Better late than never, maybe this will help someone:
I got a obdii code: P0456
I reset it and will see if it will return. I did retighten the gas cap too.
In my Kia Sedona service manual (hard copy). Here are the trouble areas...
Codes P0442, P0455, and P0456 you need to look at the following areas:
- Fuel filler cap loose or missing
- Fuel filler cap o-ring missing or damaged
- Faulty or damaged fuel filler pipe
- Leaking,, disconnected or plugged fuel vapor lines
- Fuel in lines due to faulty Rollover Valve (RV), On-Board Refueling Vapor Recovery Valve (ORVR valve)
- Canister close valve clogged, stuck open or closed
- Improperly installed purge solenoid valve (PSV)
- PSV stuck open/closed
- Faulty fuel tank pressure sensor
- Leaking canister or catch tank