Cant it just reset based on the current date. My services are a bit out of sink so I just reset it as though it has just been serviced. Full service wasn't due till June so I had an interim and check over. Next year I will have the full service done as I only use it for long runs and will probably only do 7k miles in that time. I will reset it again after the service is done.
E90 Service indicator Reset
Step 1
Insert key into slot
Step 2
Press start/stop button without depressing clutch/brake and wait for the service reminder to disappear.
Step 3
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.
Step 4
You are now in the service menu, use the toggle switch on indicator stalk to scroll up/down through the various service items.
Step 5
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
Step 6
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.
A word of warning `tho if you don`t want to alter the date of next service, you`ll need to change the date in your car to the date when the last service was done. Otherwise the computer will automatically change the date to 2 yrs from todays date. (hope that makes sense)