Code P0446
 

I have been fighting this frickin code for over 3 years on my wife's 07 h3. I blew out the vent selanoid, then i replaced the vent selanoid (with the new wiring harness), and blew out the charcoal canister as well. Then i replaced the gas cap with an oem gas cap. I have researched every thread on this interweb and apparently i am the only one that blowing air doesnt work for. I took it to my shop (not a dealer, we all know they are morons and thieves), they cleaned everything, greased fittings, they say it is an electrical code but havent got any clue. Has anyone out there found anything other than blowing air in the selanoid that has worked. My last option is to replace every electrical part in the system, but i may just send it off a bridge instead. I am not looking for suggestions or opinions, i am in need of a person who actually repaired the issue. Thank uou for any help.

I had the same issue when still under warranty.
The dealership threw every part at it. Nothing worked.
Then they traced the wire all the way back to the computer.
Ended up running an entirely new wire all the way back from the BCM.
That finally fixed the problem.

Hope this helps.

Thank you for the help. If i end up needing to run a wire, i guess she will just have to live with the check engine light.

Check the operation of the purge solenoid valve and the accuracy of the fuel tank pressure sensor. These are relatively easy to check with a proper scan tool. You can operate the vent valve with a scan tool before chasing wires. Not saying Tainter is wrong. Just a code that has many, many possibilities.

Thanks for the info. I went ahead and replaced the purge valve with oem from dealership so it is new. I dont have the scanner that can operate systems but if i take it back to the shop i will suggest it. When i replaced the valve and cleared the code, the engine seemed to run smoother but the code came back the next morning.