P0446 pops up on my car about once every two years. I clear it and it doesn't return for a long time. Maybe just a fluke error code.
Further diagnosis is suggested if it returns promptly. I believe Mike Focke has a diagram of the possible issues on his website. As I recall it could be:
*loose or failed gas cap
*vacuum line leak
* failed check valve
* failed canister
* failed vacuum actuator or fuse
Good luck!
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2009 Cayman 2.9L PDK (with a few tweaks)
PCA-GPX Chief Driving Instructor-Ret.
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