This code is an indicator of a "density sensor malfunction", meaning a bad sensor or a bad logic board.
What we can try here are some cleaning and reset steps.
First, open up the printer, and check for any internal debris such as scraps of paper, paperclip or staple, etc. Next proceed with cleaning by blowing out the Inside compartment with compressed air and checking carefully on both sides for any obstructions. Next remove all of the toner cartridges/drum assembly, then clean the metal electrical contacts on the back, as well as where they mate up inside the printer, using qtips and rubbing alcohol. Dry well, then reseat the cartridges.
Then reset the machine:
unplug power at the wall outlet
wait 5 minutes
press and hold the power/on button for 60+ seconds
keep holding while plugging back in, and for another 60 seconds after, then release
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