Msaeger is right sensor "G" is dirty or replace this happend to me last week!!!
Dirty or Defective Toner Collection Bottle Overflow Sensor
[G]
Clogged Toner Collection Coil
[E]
Toner Collection Bottle is full
System Explanation
The capacity of the toner collection bottle is approximately 1800 grams (A4 6%:650K). When the toner collection bottle starts to fill up, the toner agitator coil [A] becomes harder to turn. When this occurs, the actuator plate [B] does not rotate because the agitator coil drive gear [C] has a torque limiter, and the output of the toner collection bottle agitator sensor [D] becomes constant. At this time, the operation panel indicates that the toner collection bottle is nearly full. After this, about 200K sheets can be printed until the bottle becomes full.
When the toner collection bottle is full, the toner collection coil [E] becomes harder to turn. When this occurs, the actuator plate [F] does not rotate, and the output of the toner collection bottle overflow sensor [G] becomes constant. In this condition, the operation panel LCD indicates “Toner Full”, all copy paper in the paper feed
path is fed out, and printing stops.
If the toner bottle is not properly installed inside the toner bank, the toner collection bottle sensor [H] detects this condition and the operation panel LCD displays error messages (used toner bottle is not set correctly).
[Action]
Change toner collection bottle if full.
Clean and/or replace the Toner Collection Bottle Overflow Sensor
Clean and/or replace the toner collection coil.