K2 Plus Combo - TL4856 - Filament not detected by CFS

Issue

When you insert a roll of filament into the CFS and push the filament into the PTFE inlet tube, the filament is not taken in, the motor does not run and the white LED blinks as it would for an empty slot. 

In some cases, the CFS does grab the filament, and runs it back and forth, however the white LED light on the front of that slot continues to blink "empty", the display screen does not show any filament is loaded for that slot, and you can not edit the filament details for that slot on the screen. 

Cause

The inlet filament sensor that detects the presence of the filament is worn-out or jammed. 

Fix

To identify a worn sensor, load filament into the PTFE tube, then move the tube back and forth whilst looking down the gap in the front of the CFS where the tube leads. If worn-out, you should see a blue LED that goes on/off as you move the tube (the blue LED will stay on all the time if the sensor is working normally). To replace a worn sensor within warranty, contact Creality chat and ask for a CFS Independent Filament Inlet Module (4004010264). The process to swap it out is detailed here and video is here.

To identify a jammed sensor, you will need to remove the module from the CFS (steps here and here), unscrew the two Philips screws holding the sensor PCB to the module, and check that the metal arrow-shaped tag is moving freely under the spring that holds it in place. If it is jammed, clean out the filament path in the module, and reassemble it into the CFS. If the issue is not solved and your printer is within warranty, contact Creality chat and ask for a CFS Independent Filament Inlet Module (4004010264).