Hi, i previously had problems with my Tyre Pressure Control Monitor in my 2001 e39 m5 but now i have fixed it. So if yours is not working here is some useful infornation on how to fix it:
Firstly, turn the key to ignition (do not start it).
Secondly, hold the tyre pressure control button down for approximately 5 seconds (keep it pressed, do not let go). Then when it comes up on the OBC or computer "set tyre pressure" then you can let go.
Lastly, once you have let go of the button you can start the car and drive it around for a bit for it to set the tyre pressure control monitor.
IMPORTANT: If it comes up on the OBC or compter "tyre pressure control inactive" then follow the instructions above. If you have the car started and press the tyre control button it will say "tyre pressure control inactive" automatically and you have to follow the instructions above again to set it.
I hope this helps. Thanks