The K2 Plus CFS will not load or retract filament (codes FR2833, FR2836, FB2847…)
Guide based on the manufacturer's official documentation; usi3d has not yet verified it on a machine.
Technology: FDM · Brand: Creality · Symptoms: The multi-material system fails (does not load, cut or jams), The printer shows an error code or message, Clogged nozzle or hotend · Updated on 9 October 2026
Symptom
With the CFS (the multi-material system) the K2 Plus stops when loading, retracting or changing colour and shows a code starting with F, for example FR2833 (feed issue), FR2832 (retract issue), FR2835 or FR2836 (the filament does not reach the hub or the extruder sensor), FR2849 (it cannot return to the hub), FB2847 (filament tangled) or FM2857 (feeding motor overloaded). The CFS light turns red.
Likely causes, from most to least likely
- The filament is tangled or knotted on the spool, or the spool turns badly inside the CFS because it is damaged, deformed, or too small or too large.
- Too much resistance along the path: long, sharply bent or worn PTFE tubes, especially the section over the cable chain and the one entering the extruder sensor.
- A PTFE tube has come out of its pneumatic fitting (FB2844) and the filament keeps feeding.
- The filament is stuck or deformed in the extruder (clogged nozzle or tip chewed by the gear) or in the buffer.
- Debris in the CFS hub stops its switches from triggering, or a hub cable is loose.
- The first layer is squashed (layer compression), which Creality also links to loading and unloading failures.
Checks to tell which one it is
- Note down the full code (for example FR2836) and look it up in Creality's CFS error table: each code tells you on which section the filament stopped.
- See how far the filament got: whether it never left the CFS, stopped between the CFS and the extruder, or entered the extruder; Creality's guide is organised by that point.
- Check that the spool turns freely and the filament is not crossed or knotted.
- Go along the PTFE tubes: no sharp bends, fully pushed into their fittings and not worn inside.
Before you start
Before taking anything apart, cleaning or adjusting it, switch the printer off and unplug it, unless a step says otherwise, and do not touch the nozzle, the heater block or the bed until they have cooled down. If in any doubt about electricity, heat or moving parts, stop and ask a professional.
Step-by-step fix
Untangle and check the spool
Open the CFS, check that the spool turns freely and untangle the filament. Do not use damaged or deformed spools or sizes the CFS does not accept. Then press «Retry» on the screen.
Check: The load or colour change finishes without the error coming back.
If that does not fix it: Check the PTFE tubes (next step).
Check tubes and fittings
If the code is FB2844, press «Retract» (once or more) to pull the filament back and push the tube back into its pneumatic fitting. In general, avoid sharp bends and replace worn tubes. If your K2 Plus came with the 40 and 50 cm rear tubes (buffer to CFS and buffer to printer), Creality recommends cutting them to 30 and 40 cm.
Check: The filament moves forward and back without the tangle or overload warning returning.
If that does not fix it: Check the extruder (next step).
Filament stuck in the extruder
If the filament reached the extruder sensor but does not advance (FO2837), press «Retract»; if it comes out, cut off the damaged tip and load again. If not, with the nozzle hot remove the three extruder housing screws (mind the spring), separate the gear from the cover and cut the swollen section. If it is in the throat, pull it out hot with pliers or use the heated-needle method Creality describes.
Check: The filament passes through the extruder and comes out of the nozzle.
If that does not fix it: Check the buffer (next step).
Open the buffer if the filament gets caught
If the filament gets caught in the buffer when retracting, remove its screws and carefully open it along the central seam with a stiff card (it is held by clips). Cut the swollen piece of filament and pull out the rest. Do not lose the springs or fittings, and close it firmly.
Check: The filament goes back to the CFS when you press «Retract».
If that does not fix it: Clean the hub (next step).
Clean the CFS hub
Switch off and unplug the printer. Remove the three screws and the four tubes at the bottom of the CFS and take out the hub module without pulling the cable. Check the cable and its terminals, make sure the motor drive wheel turns smoothly and brush the debris off the gear and the guides of the four limit switches, which must move freely.
Check: Once refitted, the CFS pre-feeds the filament to the hub and detects it.
If that does not fix it: If the hub still fails, contact Creality support: it may need replacing.
Prevention
- Keep the PTFE tubes short and free of sharp bends, and replace them when worn: the filament wears them down.
- Use spools in good condition and of a size the CFS accepts.
- Fix layer compression (a squashed first layer) if you notice it: Creality links it to loading and unloading failures.
Still not fixed?
Tell usi3d's AI about your case: choose your printer, describe what you see and add photos if you like. It proposes checks step by step, with their sources.
Printers it applies to
Creality K2 Plus.
Official sources
This guide summarises the official documentation linked here:
This guide is general information: usi3d has summarised it from the official documentation linked here, and it may not match your model, its version or its firmware. If in doubt, follow the manual and the support of your printer's manufacturer. You decide what you do with your machine, and working on it may affect its warranty.