Nikon D850 User Manual page 338

D
Image Sensor Cleaning
Using camera controls during startup interrupts image sensor
cleaning.
If dust cannot be fully removed using the options in the Clean image
sensor menu, clean the image sensor manually (0 315) or consult a
Nikon-authorized service representative.
If image sensor cleaning is performed several times in succession,
image sensor cleaning may be temporarily disabled to protect the
camera's internal circuitry. Cleaning can be performed again after a
short wait.
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