Nikon D810 - Manual (Page 469)

445
Image Sensor Cleaning
If you suspect that dirt or dust on the image sensor is appearing
in photographs, you can clean the sensor using the Clean image
sensor option in the setup menu. The sensor can be cleaned at
any time using the Clean now option, or cleaning can be
performed automatically when the camera is turned on or off.
❚❚ “Clean Now”
Holding the camera base down, select
Clean image sensor in the setup menu,
then highlight Clean now and press J.
The camera will check the image sensor
and then begin cleaning. Other
operations can not be performed while
cleaning is in progress. Do not remove
or disconnect the power source until
cleaning ends and the setup menu is
displayed.