ScoobyBoo, congrats on replacing your purge valve / breather valve on your E46 based on the P0444 code. I also had the same error and the best advice I got was from 2 certified BMW mechanics, was to not waste any time doing diagnostics on this part since the probability that the purge valve / breather valve is bad is over 85%.
When I posted this problem on this forum (1.5 years ago), there was not enough information on this, but the only advice I got was to test valve, which I was not familiar with and not interested in doing.
I have been driving with P0444 error for over 1yr and will replace breather valve soon. Thanks for instructions on how to proceed.