Already Changed Vent Value, Still Have P0446 CEL, Clogged Vent Line?

[Ds1]

Hi All,

I have a 2001 Boxster S 6sp that was having the wookie/air blown over the bottle sound from the front- and an occasional CEL (P0446) I replaced the gas cap, for the cracked ring with a new Porsche unit, and the Fuel Tank Vent Valve (the one that is attached to the top of the filler neck right below the gas cap) and cleared the codes, but the code has returned and the sound is still there. I have heard two different possibilities- blocked fresh air vent line, or bad lower valve (not sure where this is- was a suggestion from the tech line at Pelican). I have been chasing this for a while and I don’t want to throw any more parts at it if I can help it. The blocked line sounds most likely- but how do I figure out which line is blocked to clear it?

Thanks in advance!

[JFP in PA]

P0446 indicates that the EVAP canister shutoff valve is operating below its limit value. Usually, this indicates either that the purge air line (runs up to the engine) is blocked, or the EVAP canister itself is blocked. Most commonly it is the purge air line, which can be blown out with compressed air once both ends are disconnected.