1. Press and hold the "mileage reset button" for 10-15 seconds when your ignition is on (engine must not be running).
The centre LCD display shows:
(The last 7 characters of your VIN number)
2. Release the button, every time you now press the button, it will reveal different sub sections in the 01 section as shown by 01.XX.
3. To see other menus, 03.XX - 18.XX successfully, you need to unlock it using menu 19. To go to menu 19 from menu 1, press the 'mileage reset' button again and hold for about 2 seconds.
4. The menu will show 01.__. Without pausing, keep pressing the 'mileage reset' button until you see menu 19 and stop.
5. After you stopped pressing the button, it will show 19.__ momentarily. Wait for about 1 second until it shows:
Now, without delay, press the button again and again until you reached the right code for your car. Pause after you reached the right code. Now, all the menus are unlocked. Your code can be 'calculated' from the last five digit of your VIN number for your convenience. If the last five digit of you VIN number is: 27581 for example, your code would be 2+7+5+8+1, which is 23. After you reached the right code of your car, pause until the display shows some changes.
6. To go to other menus after unlocking, press the button again for 2 seconds (until, 19.__ appears on screen again). Then stop at the menu which you want to access. For example, stop at 8.__ if you want to have a display of your instantaneous speed when you are driving. The 8.__ display will disappear quickly after you stop pressing the button. It will now appear as 8.00 which indicates that you have entered 'Menu 8'. To access sub menus, you press the button once to go from one sub menu to another. If you want to get out of "Menu 8", press and hold the button for 2 seconds and now, 8.__ will appear. Without delay, release the button and press the button until you reach the menu that you want to see.
You'll want menu 07.00, this will show your coolant temperature.
E90 Driver Information Systems
Test function Description Display
01 Instrument cluster identification - Vehicle identification number, last 5 digits
02 System test
03 Not used
04 Electric load values
05 Range consumption
06 Fuel level
07 Current display values
09 System voltage
10 Not used
12 Calculated time of arrival
13 Audible signals
15 I/O ports processor
18 Not used
20 Fuel consumption correction 20.00
This video shows you how to do it also, but a bit vaguely.