I have a 01 325Ci and found these awhile ago and they have worked fine for me:
Reset procedure for clusters with SIA IV using the reset mode.
• Ignition key must be off.
• Press and hold the trip odometer button in the instrument cluster (left button) and turn the ignition key to the first position.
• Keep the button pressed for approx. 5 seconds until one of the following words appear in the display: "Oil Change" or "Inspection" with "Reset".
• Release the reset (trip odometer ) button and press and hold again the "Reset " begins to flash.
• While the display is flashing, press the left button briefly to reset the service interval. After the display has shown the new interval, the following will appear: "End SIA".
The system can only be reset again after 2.5 gal (10 liters) of fuel have been consumed.