CFS Creality Hi Combo won't feed filament when printing

[Crazyyojik]

Hello.

I apologize if this question has already been answered, but I couldn’t find it. The problem is this:
my Creality Hi Combo printer doesn’t feed filament when printing with CFS. CFS loads filament when commanded. However, when I issue a command, either in manual mode or while printing, CFS doesn’t feed filament into the print head. The flag on the filament buffer moves down and stays there, preventing CFS from feeding filament. The extruder tries to draw filament, but since there’s no filament feeding, it slips.
Replacing the buffer with a new one didn’t help.
Updating the firmware also didn’t help.
I only use Creality filament.
Printing without CFS works without problems.
Has anyone encountered this issue? Can anyone advise me on how to fix it?

[foba_design]

Hi! Does the printer show any error code or other info when the issue occurs? You can check if there are solution on Creality Wiki - Creality Hi & Creality Hi Combo 3D Printer User Guide | Creality Wiki. Maybe this will help. Check if the PTFE tubes are connected properly with the buffer.

Best regards!

[Crazyyojik]

Hi. The PTFE tubes are connected according to the instructions. The printer doesn’t display any errors, and everything seems to be printing fine. However, the filament isn’t being fed by the buffer, causing the feed gears in the print head to slip.
I couldn’t find any similar issues on the wiki, so I asked for help here.
Thanks.

[impeeza1]

if you disconnect the PTFE tube from the hub and send a extrude command, What happen?

[Crazyyojik]

Nothing. The print head is trying to retract the filament. But because the CFS isn’t feeding the filament, the gears are slipping.

[Crazyyojik]

Basically, if you disconnect the PTFE tube from the filament buffer at the top, the filament doesn’t pull the buffer flag, and it stays in the down position. The CFS feeds filament for a while, then reports a buffer error. If you manually raise the buffer flag, the CFS stops feeding filament.
If you disconnect the PTFE tube from the buffer at the bottom, the CFS feeds filament indefinitely.

[impeeza1]

Ok, so the CFS and Buffer are working «fine» that should be the normal behavior.

also you can contact support directly:

Customer Service Updated

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[Bruno_Dini]

Hello everyone,

I am having a filament feeding problem with my Creality Hi Combo and I am trying to determine whether the problem is with the CFS filament buffer or with the CFS itself.

The printer works normally when using the external spool holder. The problem only occurs when printing through the CFS.

The CFS is recognized normally by the printer. When I select “Load” on the screen, the CFS pushes the filament through the buffer and all the way to the extruder. When I select “Retract” or “Unload,” it also retracts the filament normally.

However, during printing or when I repeatedly send manual extrusion commands, the following happens:

1. The extruder starts pulling the filament normally.

2. The buffer flag gradually moves downward.

3. The flag reaches the bottom position and remains there.

4. The CFS does not resume feeding filament.

5. The extruder continues pulling against the CFS.

6. The PTFE tube between the buffer and the extruder starts bending and compressing.

7. Eventually, the filament stops moving and the extruder starts clicking or slipping.

I have already performed the following tests and repairs:

• Replaced the complete extruder assembly.

• Cleaned and checked the nozzle, hotend and filament path.

• Opened the CFS buffer and found a broken piece of filament inside it.

• Removed the broken filament and completely cleaned the buffer.

• Confirmed that the buffer flag moves freely when there is no filament inside.

• Confirmed that CFS loading and unloading work normally when commanded from the printer screen.

• Tested printing with the external spool, which works normally.

• Replaced the CFS/buffer communication cables, but the problem remained exactly the same.

• Tested different CFS slots with the same behavior.

I have previously received the following error codes:

• FB2846 — abnormal filament buffer signal;

• FO2845 — possible extruder clog;

• FO0528 — printer appears to be printing without extrusion;

• FS2831 — CFS communication problem.

The FO2845 error seems to occur only after the buffer reaches the bottom position, the CFS fails to provide more filament and the PTFE tube becomes tensioned. There is no actual nozzle blockage when using the external spool.

The PCB inside my buffer is identified as:

MF003_BUFFER_V23

The complete buffer part number appears to be:

4004010263

Could this be caused by a defective sensor or PCB inside the buffer, even though loading and unloading from the screen work normally?

Alternatively, could the CFS load and unload correctly but still fail to receive or process the automatic feeding request from the buffer?

Is there any test I can perform to determine whether the fault is in the buffer PCB or in the CFS electronics before replacing parts?

Thank you for any help or suggestions.

[Bruno_Dini]

Hello everyone,

I would like to add an important update to my original post because I have now performed several firmware-level tests, and the problem still remains.

This is the original CFS supplied with the Creality Hi Combo, not the CFS-C.

The main symptom is still the same:

• The CFS loads filament normally.

• The CFS unloads and retracts filament normally.

• The extruder starts consuming filament.

• The buffer flag moves from the upper position to the lower position.

• The printer correctly detects that the buffer is empty.

• The CFS does not start feeding again.

• The extruder continues pulling against the resistance of the CFS until the PTFE tube bends and the extruder begins clicking or slipping.

I confirmed the buffer state directly through the Klipper console.

With the buffer flag in the upper position:

BOX_GET_BUFFER_STATE ADDR=1

buffer_state: 0x3

After the extruder consumes the filament stored in the buffer and the flag moves down:

BOX_GET_BUFFER_STATE ADDR=1

buffer_state: 0x2
empty

This confirms that the printer is receiving the buffer state change correctly.

I also tried manually enabling CFS printing:

BOX_ERROR_CLEAR
BOX_ENABLE_CFS_PRINT ENABLE=1

However, even after this command, the CFS still did not feed when the buffer changed to 0x2 / empty.

Firmware tests performed

Test 1 — Printer 1.1.0.73 and CFS 1.4.2

The printer was originally running:

Printer firmware: 1.1.0.73
CFS firmware: 1.4.2
CFS hardware/boot variant: G32

I performed a forced and targeted reinstall of the same CFS firmware version, even though version 1.4.2 was already installed.

The firmware file was verified before flashing, and the process completed successfully:

old version: cfs0_050_G32-cfs0_000_142
will update: cfs0_050_G32-cfs0_000_142
update: ok

Immediately after the reinstall, the CFS fed filament correctly once. The buffer flag moved down, the CFS motor activated, and the flag moved back up.

However, when the printer started the normal print preparation sequence, it retracted the filament and then loaded it again. After that cycle, the problem returned.

The extruder consumed the filament in the buffer, the flag moved down to 0x2 / empty, and the CFS stopped feeding again.

Therefore, reinstalling CFS firmware 1.4.2 did not permanently solve the problem.

Test 2 — Printer 1.1.0.65 and CFS 1.1.3

To rule out a compatibility problem with CFS firmware 1.4.2, I downgraded the printer to:

Printer firmware: 1.1.0.65

I then performed a targeted downgrade of the CFS from version 1.4.2 to version 1.1.3 G32:

old version: cfs0_050_G32-cfs0_000_142
will update: cfs0_050_G32-cfs0_000_113
update: ok

After a complete shutdown and restart, the versions were confirmed as:

Printer firmware: 1.1.0.65
CFS firmware: cfs0_050_G32-cfs0_000_113

I then loaded the filament normally through the CFS.

The buffer initially reported:

buffer_state: 0x3

I heated the nozzle to 220 °C, enabled CFS printing, and manually extruded filament in small increments.

When the buffer flag moved down, the printer correctly reported:

buffer_state: 0x2
empty

However, the CFS motor did not start feeding.

The exact same problem therefore occurred with both firmware combinations:

Printer 1.1.0.73 + CFS 1.4.2
Printer 1.1.0.65 + CFS 1.1.3

Test 3 — Printer firmware 1.1.0.50

I also installed printer firmware version 1.1.0.50.

With this version, the CFS initially worked. During manual extrusion, the CFS fed additional filament approximately three times. Each time, the buffer flag moved back up normally.

After those first few successful cycles, the CFS suddenly stopped feeding again.

The buffer flag moved down, the system detected the empty condition, but the motor no longer activated.

This makes the problem appear intermittent rather than being caused only by one specific firmware version.

What is already confirmed

The following functions work normally:

• CFS detection and communication;

• Manual filament loading;

• Manual filament unloading and retraction;

• Motor operation during loading and unloading;

• Filament movement through the CFS hub;

• Filament movement through the buffer;

• Buffer flag mechanical movement;

• Detection of the upper buffer position;

• Detection of the lower/empty buffer position;

• Printing from the external spool holder.

The failure occurs specifically when the CFS should automatically feed more filament after the buffer reaches the empty position.

Parts under consideration

The buffer PCB is marked:

MF003_BUFFER_V23

The complete buffer part number appears to be:

4004010263

I have already purchased a replacement buffer, but it has not arrived yet.

I am also considering the complete central CFS movement assembly:

CFS Hub Kit
Part Number: 4004010265

This assembly appears to include the central motor, filament drive system, local sensors and odometer-related components.

My main questions now are:

1. Is the buffer itself responsible for sending the automatic “feed more filament” request to the CFS, or does it only report the upper and lower positions?

2. Since the printer correctly detects both 0x3 and 0x2 / empty, can the buffer PCB still be defective or intermittent?

3. Could the CFS Hub Kit, PN 4004010265, be responsible for this behavior even though manual loading and unloading work?

4. Could the odometer or one of the photoelectric sensors inside the hub cause the CFS to feed a few times and then stop?

5. Is the automatic feeding motor controlled directly by the CFS mainboard, meaning that the mainboard may be the actual defective component?

6. Which part would be the most logical replacement:

• Filament Buffer, PN 4004010263;

• CFS Hub Kit, PN 4004010265;

• Hub photoelectric/odometer board;

• CFS mainboard;

• Complete CFS unit?

7. The CFS also has an external power input. Is there a safe diagnostic procedure using the official external 24 V power adapter, or could this create a dual-power condition when the CFS is connected to the Hi Combo?

At this point, the same failure has occurred after a clean firmware reinstall, after a CFS firmware downgrade, and with several printer firmware versions.

Any technical information about which component interprets the buffer signal and commands the hub motor would be extremely helpful before I continue replacing parts.

Thank you.