I have been trying to solve this one for over a year, with no luck. I car runs fine and driveability has never been an issue. However, outside of being an annoying dash light, I can not pass a Missouri Emissions Inspection with the CEL, and since the tags are 4 months overdue, I'm hoping that someone can help. The following is the list of parts replaced:

fuel cap
fuel tank pressure sensor
vapor canister
purge valve/solenoid
vent valve/solenoid
PCV hose

Thanks,
Justin

 

Welcome!

A typical point of failure is the O-ring between the canister and the valve.

Somewhere there is a leak, a tube may be broken or a connection not secured or a valve stuck open.

 

Welcome to the site!
X2 on the leak as I'm sure you've read this but I post the link for other interested parties.

Also check for loose wires and ground connections

https://www.obd-codes.com/p0455

 

Thanks. I'll check that. I remember when I changed the vapor canister, that one on the lines into the canister did not fit very well with a supplied rubber grommet. I believe that I removed it, but I know I kept it. I'll double-check to verify that is what I did, and install if that is the case.

 

Some have reported using 2 O-rings worked.