The button is under a small aluminum cap that is drilled for a wire and lead seal. In the picture, that wire seal is gone. Unscrew the aluminum cap from the plastic thread facing forward on the box and use a small probe to push down on the white plastic button underneath. You will here a "click" and that sets the timer again to start the mileage interval before the light comes on again. Alfas use this, too. -Peter
Great info. Thanks So anyone know what goes on inside the box? Does it have a separate ODO link to the gearbox, or is all electronic taking feed from the dash ODO (looks too big for that)?