I found this one the forums.
Originally Posted by ENINTY
This is from the sticky somewhere. I copied it to Word and saved it as a file so I would loose it. Works perfect.
Guys I looked everywhere (maybee not hard enough ) for a DIY service reset for E90 but couldn`t find one. So decided to try the E60 DIY which wasn`t too far off. I realise most cars are still under warranty but I will use this to replace my own brake pads and microfilter instead of being fleeced by the $tealers.
Insert key into slot
Press start/stop button without depressing clutch/brake and wait for the service reminder to dissapear.
Immediately after service reminder goes out, press and hold the odometer reset. After 3 secs a warning triangle will appear, keep the odo. button pressed and after another 2-3 secs the Oil can will appear. I f you hold it too long (10 secs in total) you will overshoot the runway and some German writing will appear giving the software level/ can bus etc. of the car. Go back to the beginning and start again.
You are now in the service menu, use the toggle switch on indicator stalk to scroll up/down through the various service items.
When you have the item you want to reset showing, press the BC button on end of indicator stalk. Reset should now appear in the display. Press in and hold the BC button for 2-3 secs and a clock will start whirling around and hey presto, its done
You can now either scroll up/down to select another item (as in step 4) or you can press the start/stop button to exit.
Sorry if this a re-post guys but like I said I couldn`t find it anywhere.
I accept no responsibility if you break your car, this is done at your own risk.