How to unlock the e39 On Board Computer secret features.
1. Push the right button. Hold it pushed in. Don't release it! Your display will change from whatever it showed before (That should be: Check Control OK) to: Test No.1
When it says: Test No.1
2. Push the left button (short push, like a mouse click). It should show your Car ID. (last seven digits of it, 2 letters and 5 numbers). You gotta add those five numbers up (e.g. DW57384 = 5+7+3+8+4 = 27)
4. Push right button till Test No.19 shows in the Display
5. Push left button as often as the number is you got (in my example 27times). The display should show 27!