986 Forum - The Community for Porsche Boxster & Cayman Owners - View Single Post

PBoxstar · 04-17-2017, 08:37 AM

Hi All,

My 99 Boxster 2.5L is unhappy and throws DTC P0446 ("Evaporative Emission System Vent Control").

I researched the issue for a while and decide to take a look at the Evap system by the tank filler neck.
Here is what I found out so far:
The valve attached to the carbon canister seems to be working, I removed the valve and applied 12V and Ground to the two leads. The valve actuates and closes the plunger/diaphragm. Are there any other things I should check?

I also removed the other valve which was attached to the filler neck (see below).
When I blow in the red part (green arrow), the air flow is blocked. Once I push in the black plastic piece (yellow arrow) air can flow through the valve from green to green arrow. I assume that is correct behavior.

While I was on it I also removed the carbon canister. I can blow air through the hose (from green to green arrow) so it doesn't seem like there is blockage in there either...

How can I debug the actual carbon canister?

All of the other hoses are attached to the vehicle and lead to and from the tank I presume...?

What else can I do to debug the fault? I'm kind of running out of ideas....

Any help is appreciated at this point!

04-17-2017, 08:37 AM	#1
PBoxstar Registered User Join Date: Sep 2016 Location: Campbell, CA Posts: 13	Need Evap Vent Control Debug Help! Hi All, My 99 Boxster 2.5L is unhappy and throws DTC P0446 ("Evaporative Emission System Vent Control"). I researched the issue for a while and decide to take a look at the Evap system by the tank filler neck. Here is what I found out so far: The valve attached to the carbon canister seems to be working, I removed the valve and applied 12V and Ground to the two leads. The valve actuates and closes the plunger/diaphragm. Are there any other things I should check? I also removed the other valve which was attached to the filler neck (see below). When I blow in the red part (green arrow), the air flow is blocked. Once I push in the black plastic piece (yellow arrow) air can flow through the valve from green to green arrow. I assume that is correct behavior. While I was on it I also removed the carbon canister. I can blow air through the hose (from green to green arrow) so it doesn't seem like there is blockage in there either... How can I debug the actual carbon canister? All of the other hoses are attached to the vehicle and lead to and from the tank I presume...? What else can I do to debug the fault? I'm kind of running out of ideas.... Any help is appreciated at this point!