CEL P0446 -stymied!

[Bachster]

I have a 98' Boxster 2.5 with 75,000 mi. Since purchasing it a year ago, the CEL has come on about once every 8-10 wks with the P0446 code, often shortly after a re-fueling. I've replaced the gas cap, made sure it's tightened properly after each re-fueling, had the vacuum system checked by my Porsche mechanic, no problems showed up. Today the CEL (with the same code) appeared again. Does anyone have any insights as to what may be going on? Thanks.

[Loren]

P0446 - EVAP Canister Shutoff Valve (Function) - Below Lower Limit

The task of the shutoff valve is to seal the purge air line to the EVAP canister during the fuel tank leak test.

Potential causes:

Purge air line blocked.

Flow resistance of EVAP canister too high.

1 - EVAP canister purge valve

2 - EVAP canister

3 - Purge air

4 - Tank

5 - Pressure sensor

6 - Shutoff valve

7 - Operating purge valve

8 - To intake manifold

9 - Vacuum control valve

[Bachster]

P0446 - EVAP Canister Shutoff Valve (Function) - Below Lower Limit

The task of the shutoff valve is to seal the purge air line to the EVAP canister during the fuel tank leak test.

Potential causes:

Purge air line blocked.

Flow resistance of EVAP canister too high.

1 - EVAP canister purge valve

2 - EVAP canister

3 - Purge air

4 - Tank

5 - Pressure sensor

6 - Shutoff valve

7 - Operating purge valve

8 - To intake manifold

9 - Vacuum control valve

Thanks very much for the detailed reply.

I plan to follow this up w/ my mechanic.

[jvcuenca]

so, how do you fix this problem? thanks

P0446 - EVAP Canister Shutoff Valve (Function) - Below Lower Limit

The task of the shutoff valve is to seal the purge air line to the EVAP canister during the fuel tank leak test.

Potential causes:

Purge air line blocked.

Flow resistance of EVAP canister too high.

1 - EVAP canister purge valve

2 - EVAP canister

3 - Purge air

4 - Tank

5 - Pressure sensor

6 - Shutoff valve

7 - Operating purge valve

8 - To intake manifold

9 - Vacuum control valve

Thanks very much for the detailed reply.

I plan to follow this up w/ my mechanic.

[GimpyB0y]

so, how do you fix this problem? thanks

I too have had this problem. It occurs on and off for three years. Dealer can't fix. I have had the EVP Canister replaced twice. Appears to be related to overfilling the gas tank. When there is gas collected up the tube it causes the fault. Need to empty tank and refill normally. Once I have driven through one or two tanks of gas the code clears.

[jvcuenca]

so, how do you fix this problem? thanks

I too have had this problem. It occurs on and off for three years. Dealer can't fix. I have had the EVP Canister replaced twice. Appears to be related to overfilling the gas tank. When there is gas collected up the tube it causes the fault. Need to empty tank and refill normally. Once I have driven through one or two tanks of gas the code clears.

ok, I'll try that onceI replace my canister. I tend to overfill the gas tank as well..Might as well changed it since my car is over 10 years old...