P0455 is a pain sometimes because you have a leak in a purge valve or a rubber fuel vapor hose, etc., and you will need to identify all the parts of the system, and then trace each one of them in turn.

BTW, as an aside, I tested when the DTC's clear & set by removing my gas cap for six months as described in this thread:
- What happens with the P0455 diagnostic trouble code when the gas cap is missing (1)

wik009 said:

Has anyone had experience with CEL code 455?

Click to expand...