DIAGNOSIS The printer's optical ink level sensor is dirty or blocked. Ink dust or paper fibers trigger a false empty reading.
FIX Power off the printer. Open the front cover. Remove all ink cartridges. Use a clean, lint-free cloth slightly dampened with distilled water. Wipe the copper contacts inside each cartridge slot and the plastic sensor window next to the slots. Let it air dry for two minutes. Reinstall cartridges firmly until they click. Close the cover and power on.
IF THAT DIDN'T WORK One cartridge chip may have failed. Swap the suspect cartridge to a different slot. If the error follows the cartridge, replace it. If the error stays in the same slot, the printhead carriage circuit board needs service.
HEADS UP Never use isopropyl alcohol on the optical sensor window. It can cloud the plastic and make the problem permanent.