Maybe 15 minutes
I am, like so many here, thankful for the original post and everyone else that weighed in. I am on my 3rd 540i, and this one displayed the classic symptoms, meaning the fan had a mind of its own. But I also had some werid throttle issues that I was thinking meant a replacement throttle or something. FSR change was amazing. Fixed the fan, AND a ton of the throttle issues. This is not an easy fix, if you are tall, but the OP was SO helpful, I persevered and got it done. THANKS to all.