CFS: what its lights mean and what to do if the printer does not detect it
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 · Updated on 9 October 2026
Symptom
The slot lights on the CFS (Creality's multi-colour system) flash or stay red, or the CFS turns its screen on and pre-feeds filament but the printer does not detect it.
Likely causes, from most to least likely
- Red single flash: there is filament in the slot but not in the hub; loading failed and the filament stayed inside the CFS.
- Red double flash: there is filament in the slot and the hub, but the printer cannot load or unload it.
- Solid red: the slot is empty but the hub detects filament. Red breathing: the slot should be printing but has no filament or has run out.
- Four red lights blinking in sequence: communication has failed and the printer does not detect the CFS; usually the 485 communication cable is loose or broken.
- A faulty 485 communication board (on the CFS or the printer) or a faulty mainboard.
Checks to tell which one it is
- Compare each light's colour and rhythm with Creality's table: solid white is normal idle with filament; breathing white, printing; four white lights in sequence, communication fine with no filament.
- If all four red lights blink in sequence, the fault is communication with the printer.
- With filament in some slots, it is normal for empty slots to stay unlit; but if, with all four empty, one light never comes on, that feeder is not powered properly.
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
Red single or double flash: follow the filament
See how far the filament got: if it does not leave the CFS or does not reach the hub, check that the spool is in good condition and turns freely without tangles, and that the PTFE tubes have no sharp bends and are fully seated. Then try loading again; Creality's general loading and unloading guide says what to check depending on where the filament stopped.
Check: The light returns to white and loading completes.
If that does not fix it: Check the hub (next step).
Solid red: check the hub
If the slot is empty but the hub detects filament, check whether a piece is left inside. To clean it, follow Creality's clogged hub guide with the printer switched off and unplugged.
Check: With the slot empty, the light is no longer solid red.
If that does not fix it: Contact Creality support.
Four reds in sequence: reconnect the 485 cable
With the printer and the CFS switched off, disconnect and reconnect the 485 communication cable between them. Power on and check whether the printer detects the CFS.
Check: The lights turn white and the printer shows the CFS.
If that does not fix it: Check the cable and boards (next step).
Check the 485 cable and boards (experienced users only)
Creality checks with a multimeter, always with everything switched off, the 485 cable's continuity and the resistance of the communication boards: on the CFS about 120 Ω with the buffer connected and about 36 kΩ without it; on the K2 Plus about 2.5 kΩ. Depending on the result, the cable, a 485 board or a mainboard is replaced. If you are not experienced with a multimeter, do not do it: contact Creality support.
Check: With the faulty part replaced, the printer detects the CFS.
If that does not fix it: Contact Creality support.
A slot that never lights up
If, with all four slots empty, one light never comes on, that feeder is not powered properly: contact Creality support to have it checked.
Check: After the repair, all four lights respond.
If that does not fix it: Contact support again.
Prevention
- Only plug or unplug the 485 cable with the devices switched off.
- Use spools of a compatible size and supported filaments in the CFS: do not load TPU or other flexibles.
- Keep the PTFE tubes short, without sharp bends and fully seated.
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, K2 Pro, K2 Plus, K2 SE, Hi, Ender 3 V4, K1, K1C and K1 Max.
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.