Resetting Oil Service Light on your 2002 - 2006 Cooper and Cooper S Hatchbacks, and 2005 - 2008 Cooper and Cooper S Convertibles:

1) Press and hold the trip button
2) Insert key and turn to position 1
3) Watch for RESET to appear
4) Release the button, then press & hold it again
5) Wait for the RESET to flash
6) Release the button, and then press & release (once only)
7) Service interval should then be reset to next interval

If that didn't work, try this:

1. Push the Trip Button
2. Turn ignition key to position 1 and 51A will appear to left of mileage
3. Release trip button
4. Wait 3 seconds
5. Push trip button
6. Wait (5-8 seconds) for RST to appear in left corner
7. Release trip button
8. Push trip button
9. 15000 will appear as new service interval
10. Release trip button

Or this:

1. Press and hold the trip odometer button.
2. Insert car key and turn it to the fi rst position (not the second position).
3. You will see 51A come up in the trip odometer area.
4. Release, then press and hold again.
5. Watch for the word “RST” to appear on the Odometer indicator.
6. Release, then press and hold again.
7. Wait for the “RST” message to fl ash.
8. Release, and then press & release (once only).

For the Gen 2 MINIs (2007+ R56, 2008+ R55, and 2009+ R57, see this article.