Homing error Z #31301 (CORE One) #26301 (MK4S) #13301 (MK4)…

What happened?

The printer is showing the message: "Failed to home the extruder in Z-axis, make sure the loadcell is working".

Error name: Homing error Z

Error code: #31301 (CORE One) #26301 (MK4S) #13301 (MK4) #28301 (MK3.9S) #21301 (MK3.9)

How to fix it?

Forces from filament feeding

Make sure that the extruder is not exerting force to pull down the filament. If you are not sure, try to unwind it a small amount on the spool when testing the Z-axis.

In case you have an MMU, Enclosure, or custom setup where the filament is fed to the extruder by a PTFE tube, make sure that the extruder does not have to exert force to pull down the tube.

Trapezoid nuts

On CORE One, move the bed down, open the trapezoid nuts, and check if they can move freely along the threaded rods.

It is also possible to lubricate the Z-axis lead screws as instructed in Regular printer maintenance (CORE One) under "Axes check - Z-axis leadscrews"


Rear motor	Front left motor	Front right motor

On MK-series printers, check if the trapezoid nuts have the correct orientation.

Loadcell troubleshooting

If the above checks do not solve the issue, it will be necessary to troubleshoot the loadcell and the components surrounding it. The dedicated loadcell troubleshooting article contains all the points to check and that can be related to this error.

7 comments

JellyTitan

•

For the MK4S, I was able to fix this error by tightening the thumb screws on the nozzle. They had come loose over the course of 6 months, and this was allowing the nozzle to move just enough to cause problems. (I think these loose screws also caused my issues with first layer calibration, crashes during homing, and loadcell calibration).
You can see the thumb screws in assembly instructions step 27, including all three photos, for a guide on proper position and tightening the thumbwheels: https://help.prusa3d.com/guide/5-nextruder-assembly_434014

yavaya

•

Try to Bed Level Correction.

Simmen

•

The newest firmware fixed it for me

fscats

•

I am also getting this error on my new 3.9 upgrade, and have to re-initialize the machine after each print. After I "Factory Reset" the machine, the first print works perfectly, but after that it stops about 20mm above the plate on the next print and proceeds to try to do the nozzle cleaning for the next print at 20mm above the plate. Nothing I can do resolves this until I "Factory Reset" the machine. My (cardboard) spool is on the standard Prusa Mk3s holder, and is definitly NOT causing excessive friction.The error also occurs if after doing the Factory Reset and successfully Self Test including successful Z check, I manually trigger the Calibrate Z axis, at which point it sets zero to about 20 mm above plate, if I do yet another Calibrate Z it sets zero to even higher up.

fscats

•

Note that none of the suggested fixes in the article work for me. Also, cutting the filament just above the print head has no impact, so it is not an issue of resistance from the filament causing an error with the load cell. Indeed, from the symptons here I verry much doubt my calibrate Z problem has anything to do with the loadcell, unless it randomly triggers almost every time the regular (not full self test after a factory reset) calibrate Z raises the hotend to maximum height then lowers and stops at 20 mm above the heat bed. @docbadger says that loosening the screws on the Z motors by a quarter turn resolved a slightly different calibrate Z issue, which I will try pending ANY response from Prusa on my issue.(also note: I uploaded a Youtube video at https://youtu.be/q70-p2tlZWw showing the factory reset, successful self test, then calibrate z resulting in issue).

fscats

•

Tried @docbadger suggestion of losening the Z Motor mounting screws, this did not help.

fscats

•

Fixed issue thanks to recommendation from a Prusa support person to try the 5.10 alpha 2 firmware. After update, preceeded by one more factory reset, the z axis calibrates correctly in both the full test mode which worked before and the Calibrate Z function which didnt. Was able to print serveral models in a row without Z error.

guoli

•

i had exact the same problem as you.
and finally 5.1alpha2 as you said helped for me as well! Thank you for writing it here :)

miranstan

•

I am having the same issue as Leonardo, my filament is loaded properly and isn't too hard to pull down, but I still need to push filament down to get a print going. Anyone have any tips?