DIAGNOSIS The printer's estimated toner level counter has tripped. This is a prediction, not a real-time measurement. Printing can continue.
FIX To suppress the message temporarily, open the front cover. Wait for the drum unit to stop moving. Close the front cover. The message will clear for a period. To check the actual counter, print a settings report. Navigate: Menu > Reports > Settings. The 'Toner Remaining' percentage is an estimate. When it reaches 0%, the printer may refuse to print.
IF THAT DIDN'T WORK The toner cartridge may have a faulty chip. Some aftermarket cartridges trigger early or inaccurate warnings. The printer will still function, but the message will persist. Consider resetting the toner gauge. With the printer on, open the front cover. Press and hold the 'Go' button for 10-15 seconds until all LEDs light. This resets the counter, but use is not guaranteed with all cartridges.
HEADS UP Printing with a genuinely empty cartridge can damage the drum unit. Inspect print quality. Fading or vertical white streaks indicate true exhaustion. Replace the cartridge immediately.