DIAGNOSIS The electrical contacts are dirty. This happens between the printhead and the cartridges or between the printhead and the printer.
FIX Power on the printer and open the front door. When the cartridge carriage moves to the center, unplug the printer. Remove all ink cartridges. Use a clean, lint-free cloth slightly dampened with distilled water to wipe the copper contacts on the cartridges and inside the carriage. Let everything air dry for 5 minutes. Reinstall cartridges firmly until they click, then plug the printer back in.
IF THAT DIDN'T WORK The printhead itself may be failing. Run the printer's built-in printhead cleaning utility 1-2 times from the control panel under 'Tools' or 'Printer Maintenance'.
HEADS UP Do not use alcohol or abrasive wipes on the contacts. If the error persists after cleaning, one of the cartridges or the printhead is likely defective and needs replacement.