(1) Check if it ran out of the material for left extruder in filament chamber. Reload material as needed.
(2) If the error code cannot be cleared or issue persist, unload the filament in left extruder assembly, remove the tube between filament box and printer, and cut a piece of filament. Then, enter “system” - “machine” - “factory testing” (Figure - 1), scroll down and find “Material Shortage Sensor State”, and click “Test”. When inserting the filament (Figure - 2) and it is detected by the sensor, “L: OK” will be displayed in touch screen (Figure - 3). After that, remove the filament, “L: NOK” (Figure - 4) should be displayed in touch screen.
(3) If the status of “L - Material Shortage Sensor State” doesn't change, use knob wrench to remove the back cover of printer. Locate and re-plug plug-J12 (Figure - 5) in lower left corner of main board. Then, do the step (2) again, and check if issue had been solved.
(4) If issue persist, please check the filament absence sensor of left extruder, re-plug the plug of sensor or replace the sensor. (Step of replacing filament absence sensor)
(5) If issue persist after replacing the sensor