Hi, I have a 98 M Roadster with 144,000 miles. For the last 5 years or so my CEL has gone on and off. I took it to an independent shop and they replaced the charcoal canister but that didn't fix it. I bought a code reader from AutoZone and read P0446. I did some Internet research at the time and it seemed it was not a big deal, maybe a setting in the software was set a bit too aggressively from the factory. I tried a new gas cap and that didn't help either.

I got to researching again tonight and found a reference here:


that indicated it might be a stuck N80 valve. Problem is, I don't know where that valve is. Can I take it off and clean it out? Any thoughts on P0446?