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No filament during print but not blocked  

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fMD
 fMD
(@fmd)
Member
No filament during print but not blocked

Hi all,

I have an MK3S that has been printing fine until recently. 

I can swap the filament and nozzles and it heats fine and filament extrudes well during the swap. But when I got to print nothing comes out. It asks me to unload and reload the filament at the beginning of the print and I do, and filament comes out again, but it still doesn't print. Using PLA at 210-220c. 

 

Any ideas? Thanks!

Posted : 09/02/2026 4:49 pm
fMD
 fMD
(@fmd)
Member
Topic starter answered:
RE: No filament during print but not blocked

 

Posted by: @fmd

Hi all,

I have an MK3S that has been printing fine until recently. 

I can swap the filament and nozzles and it heats fine and filament extrudes well during the swap. But when I got to print nothing comes out. It asks me to unload and reload the filament at the beginning of the print and I do, and filament comes out again, but it still doesn't print. Using PLA at 210-220c. 

 

Any ideas? Thanks!

I disabled the fil sensor and it's working now. But the sensor showed 1 so it was detecting filament. Is the next step to clean the sensor? Thanks!

Posted : 09/02/2026 9:30 pm
Diem
 Diem
(@diem)
Illustrious Member

Yes. Fine stringing or dust can jam the moving part causing false reporting.  First try a blast of compressed air...

Cheerio,

Posted : 10/02/2026 5:40 am
fMD
 fMD
(@fmd)
Member
Topic starter answered:
RE: No filament during print but not blocked

Thanks! I did this but it stopped working again even with the sensor turned off. What's my next step? Thanks again

Posted : 10/02/2026 2:40 pm
Diem
 Diem
(@diem)
Illustrious Member

Check the sensor is reporting correctly (LCD menu) as the next step is disassembly, checking for  'sticky' dust/debris and worn parts.

[This is where a spider attaching one end of a web to the filament can cause disproportionate problems - the web is pulled into the sensor and, being sticky, glues the wrong things together.]

But first do a cold pull in case of a partial blockage - unlikely but easy to do without resorting to the screwdriver...

And, incidental, the filament change at the start suggests you might be using a multi-extruder preset with a single extruder printer..?

Cheerio,

Posted : 11/02/2026 8:29 am
fMD
 fMD
(@fmd)
Member
Topic starter answered:
RE: No filament during print but not blocked

Thanks. Could it still be the sensor even though I disabled it? 

Good catch. I have a mmu attached but never got it to change filaments correctly, so I gave up on it. This error asked me to reload filament though.

Posted : 11/02/2026 12:58 pm
Diem
 Diem
(@diem)
Illustrious Member

even though I disabled it?

That's why I suggested the cold pull - but we already know this is a compound problem with issues interacting - check the sensor is reporting correctly with and without filament a few times...

And you may find the reload problem goes away with the correct preset.

Cheerio,

Posted : 11/02/2026 8:54 pm
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