i have a 2008 scion tc with a injen cai and cat back exhaust. about a month ago i refueled my car while it was running because it was FREEZING outside. DUR DUR. and about 100 miles later the CEL came on. the codes that came up is p0441 p0455. all of which is a evap leak code. All the lines on my intake are connected. i also cleared the codes and disconnected the battery and let it run for 15 mins to allow the car to calibrate itself to the intake. But still after driving for a few miles light comes back on. some people tell me it most likely is the gas cap. it does open pretty easily. i also noticed when i look down the gas fill tube that there is NO anti syphon flap. i never noticed if there was even one.
Any assistance could help alot
Thanks

do u make sure u hear 3 clicks from gas cap when u tighten it?

yup still same thing

BUMP.

I've been having this problem (my tC is stock with 58k). I just ordered a new gas cap, hoping that helps, but I'd like to explore other options before going to a dealer.