Cause of codes P0441 and P0455 on a 2007 Toyota corolla

Question

When I first checked the gas cap and tightened it, the codes went away, but came back two days later and wouldn't go away. I checked the filler pipe and could find no corrosion or any other problem

Answer 1

P0455 Evaporative emission leak (large leak detected)

P0441 Evaporative emission leak incorrect purge flow

The cause for this code is P0441, without a purge flow the FTP (fuel tank pressure sensor) is expecting to measure vacuum decay to report the amount of EVAP leak. No purge flow going into the fuel tank, the ECM thinks there is a large EVAP leak, The fix is go to the purge valve , either the hose for it is disconnected (which is very common during a airfilter check)