I just registered only thank you, pgnuta.
I am so glad that you wrote all this down, because it seems like my E53 X5 with M62B44 seem to have the identical symptoms and from what I have checked so far I seem to have the exact same issue you had. What I have read here is very helpful to my case. I know that you sir are no longer active, but I just want to encourage more people to document their troubleshooting in a similar fashion. You guys might think nobody will ever use it, but years later some bloke from the opposite side of the world would speak English and he'll be browsing for hours to find out what's wrong with his bimmer.
Cheers from Poland
