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Filament Sensot not working  

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Polysulfide
(@polysulfide)
Active Member
Filament Sensot not working

This seems to coincide with upgrading to FW 3.14 but could just be a coincidence since I haven't used the printer in a while.
When autoloading filament the filament isn't detected and the extruder doesn't engage.
This isn't a huge deal, I can manually load filament.
- Have no "unload" ability because it doesn't know its loaded
- Printing works fine
- Can't perform 1st layer calibration which is kind of essential for new filaments.

The wires are all good and getting 5v from the board.

I can't find the replacement part in the store.  It says "PRUSA Laser sensor" rev 0.2e

It has 4 pins.  It looks like possibly the IR sensor might fit physically but it only has 3 pins.

Are there any known issues with the FW that could cause this?  If not, how can I get a replacement sensor?

This topic was modified 5 months ago by Polysulfide
Posted : 03/12/2025 8:18 pm
1 people liked
Bass.Boi
(@bass-boi)
Member
RE:

I have exactly the same problem ony MK2.5S.

Everything was working prior the update, i did print the same day and it was fine.

Updated from 3.14.0 to 3.14.1 and it looks like the sensor is not detected anymore.

I will probably downgrade. 

Don't wanna buy new printer just yet as mine is working fine.

This post was modified 5 months ago by Bass.Boi
Posted : 17/12/2025 8:12 am
1 people liked
lkp
 lkp
(@lkp)
Member
RE: Filament Sensor not working

I had the same issue with the 3.14 with the filament sensor not being detected. I have an MK3

Posted : 07/01/2026 10:58 pm
1 people liked
Polysulfide
(@polysulfide)
Active Member
Topic starter answered:
RE: Filament Sensot not working

No answer from Prusa on the community or support for a year!

I bought an AnyCubic.  I'm so freaking happy.  Prusa was my first and I didn't know what I was missing.  I can't believe I keep upgrading that POS year after year.

They lost a lifetime fan and everyone I can influence over an ounce of communication.

Posted : 17/03/2026 5:03 pm
tlocke01
(@tlocke01)
Member
RE: Filament Sensot not working

Does anyone have a solution for this? I just updated to 3.14.1 and now I can no longer autoload filament and worse I can't turn off the sensor in settings so I can't manually load filament either.

Posted : 08/04/2026 10:14 pm
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