Machine cannot work properly and there's a message check hopper connector. what exactly hopper connector is?

General condition
1) Is the developing assembly locking plate mounted correctly?
NO: Mount the plate correctly.

General condition
2) Is the shutter releasing member of the hopper mouth mounted correctly
to the developing assembly locking plate?
NO: It is likely that the inside of the hopper is clogged with toner. Remove
and then mount back the shutter releasing member to remove
the clog, or replace the hopper unit.

General condition, Developing assembly toner sensor (TS1)
3) Is the developing assembly adequately provided with toner?
YES: Check the developing assembly toner sensor.

General condition, Hopper toner sensor (TS2)
4) Is the hopper adequately provided with toner?
NO: Check the hopper toner sensor.
Hopper connector, Hopper supply motor (M10)

5) Is the connection of the hopper connector normal?
NO: Connect the connector securely.
YES: Check the hopper supply motor.

I just fixed mine, it was part of the hopper system. If part of the mechanism is jammed it will flag a error code 8. The part that broke was the little black hopper unit that swings to allow the coffee ground to go down the hopper, it appears that there is a defect in the swing cover as this stainless mechanical spring will break and cause for the hopper to not move properly. What happens is when the spring breaks it caused for the hopper guide to come out of the slot and jambs, when it jambs the unit knows that it is not completing it hopper cycle and flags an error code, in this case #8. The only thing you need to do is put the hopper guide back in its slot and that's it, the only problem is it will take multiple efforts to align the cover but I found that you can fish your hand through the tray opening and guide it into place.

there is a small connector just below the toner hopper check the connector and connect it properly.

check where you put the toner, simply connect that cable. if connected then the sensors not in good position. usually such problem comes from the accessories that come with the machine such as ADF, Duplex, Sorter makes sure they are working properly.

E020
General condition
1) Is the developing assembly locking plate mounted correctly?
NO: Mount the plate correctly.

General condition
2) Is the shutter releasing member of the hopper mouth mounted correctly
to the developing assembly locking plate?
NO: It is likely that the inside of the hopper is clogged with toner. Remove
and then mount back the shutter releasing member to remove
the clog, or replace the hopper unit.

General condition, Developing assembly toner sensor (TS1)
3) Is the developing assembly adequately provided with toner?
YES: Check the developing assembly toner sensor.

General condition, Hopper toner sensor (TS2)
4) Is the hopper adequately provided with toner?
NO: Check the hopper toner sensor.
Hopper connector, Hopper supply motor (M10)

5) Is the connection of the hopper connector normal?
NO: Connect the connector securely.
YES: Check the hopper supply motor.

Main cause: The machine is not receiving toner properly because 1)The hopper connector is left disconnected. 2) The hopper motor (M9/M10) is faulty.3) The toner sensor (TS1/TS2) is faulty. 4) The DC controller PCB is faulty.
If you recently added toner, recheck that area.
Basically the copier is trying to add toner and is not getting it.

Open front cover. On the right side towards the top, there is a grayish small cover with a black phillips head screw. remove this screw. Remove the small cover. Underneath this cover is a plug that connects the toner hopper to the machine. Reconnect this harness plug to matching plug on machine harness. Reassembly is reverse. Hope this helps.

Have you checked the toner hopper connector?, If it is not connetcted it properly it will throw a error code E020, The connector is right behind the toner hopper on the right side.

Di200 [Subject] "Please Add Toner" is displayed even though the toner bottle is full. The ATDC circuits have been checked and the main and sub hopper motors are good. [Description] "Please Add Toner" is displayed even though the toner bottle is full. The ATDC circuits have been checked and the main and sub hopper motors are good.
[Solution]
CAUSE: Inside the sub hopper, the magnet (P/N 9326-2900-06) may be catching on the inside of the hopper, preventing proper actuation of the Sub Hopper Toner Empty switch.

SOLUTION: Make sure that the actuator can move freely up and down when no toner is in the sub hopper.