Originally Posted by pizzaguy

The 0455 means there is a leak so bad, that when the evap system tries to pressurize the tank for the evap test, it cant because SOMETHING is bleeding the air out just about as fast as it is pumped in.

WARNING: Do not overlook the chance that the tank is pressurizing fine, and the SENSOR is bad, lying to the ECU.
You can work to "fix the leak" all you want to, but if there IS no leak, you are wasting your time.