I need some help trying to solve a p0455 (tank vent system, major leak) code on a 2000 base Boxster, Tiptronic. I'm smoke testing the evap system and the only leak is from a vent hose (?) behind the rear bumper.
Testing procedure: applied 12v supply (old wall wart with alligator clips) to the purge valve below left intake to activate it. Removed its hose from just past the throttle body and attached my smoke machine (0.5psi pressure) into that hose. I removed inner front right fender shroud to see the carbon canister and lines, and the battery/tray to see the top of the tank connections. I'm testing in a pitch black garage with a handheld work light to see the smallest traces of smoke.
The only smoke I detected was coming from the bottom rear corner of the bumper. Scratching my head, I removed the cover and it is coming from this line, which is open to atmosphere.
What is this, and what does it connect to at the other end? Can anyone point me to a diagram? It disappears into the area above the exhaust on the left side of the car, hidden up above the heat insulation. So I can't easily trace it without removing a bunch of things.
Any idea what is happening here? Is my testing procedure incorrect and I'm letting smoke into something I shouldn't? Is there a failed component somewhere that is letting things flow into this line? Should it be capped?
I temporarily plugged it to do the test again. I can't find any leaks anywhere else.
Help!