I know it's an old thread, but I fugured I'd put in mt two cents... I bought my 325I used with 87k and less than a week later my SES light came on. I went to a local Pep Boys or O'rileys or one of those auto part chains, and bought an ODB 2 scanner for about 125$. P0444 and i think p2444 were the codes I was throwing (MAF and EVAP PURGE). Natutally,I thought it was the end of the world!
Well I did a little research, and thanks to JBEUROTECH'S "test first" antics, I did just that. I had a Little trouble testing the lines that run to the valve itself, but only because it's kind of a tight fit, but when I found they were in good order, I went ahead and ordered the purge valve for like 95 bucks on eBay.
Once I got the valve in, and since I had already pulled it all apart and seen how it all went together, I felt I had a bit of an advantage having seen how the things the "whole deal works." Obviously the first thing I did I was to disconnect the negative battery terminal. Then I just just removed the airbox, and all the little odds, and ends and ducting to expose the EVAP PURGE or fuel breather valve.
Once I removed all the little fastening clips from the electrical connector and the fuel lines, I just pulled the faulty valve out. Next, I put a very light coat of petroleum jelly on the fuel valves in / out lines as well as on the lines themselves. I Then just pushed the new valve in it place, and put some dilectric grease on both the male and female electric connectors, and secured it all back in place.
After I had the part installed successfully, I cleaned up the airbox and put it all back together.
I reconnected the battery and re-scanned for any potential remaining fault codes, and found not a single one!
Even though this process has been dealt with before in this thread, I figured I'd throw my experience on here in the hopes that it may help someone else out there. Additionally, I believe the purge valve fault was thre reason I was geting the 02 sensor fault; although I can't wrap my head around why the two would overlap but hey, I'm not complaining.
Nonetheless, this is. an extremely easy job even for a novice. Not to mention, It requires only a couple of basic hand-tools, and less than 150$ + 2 or so hours of labor.
I do hope this post can help a fellow E46'er