Selftest failed

On the Prusa CORE One, the selftest checks for issues in the assembly of the printer, its wiring, and the electronic components. It is the first part of the Calibration Wizard, which is prompted automatically when you turn on the printer for the first time or after a factory reset. After the initial calibration is completed, each step of the selftest can be initiated under LCD Menu -> Control -> Calibrations & tests. 

Selftest procedure checks

• Test of the extruder and the print fan 
• Test of the X, Y, and Z axis 
• Proper connection of the heated bed and the hotend 
• Loadcell test 
• Setting up the filament sensor 

Selftest results

During the selftest, its results are shown on the screen, indicating success or failure for each point. 

Selftest errors

Test of the extruder fan and the print fan

The Prusa CORE One selftest procedure can determine which of the fans doesn't work. Check the one that is diagnosed as not OK.

• Make sure that both of your fans are correctly connected to the LoveBoard.
• Check for any blockage that could prevent either of the fans from spinning.

Test of the X, Y, and Z axis

The printer can determine if the components are moving correctly along each axis. 

In case of an issue on the X-axis, or on the Y-axis, make sure that there is no obstacle to the movement, and readjust the belt tension.

Also, test the printer movement, with the stepper motors temporarily disabled (LCD Menu -> Control -> Disable Motors), moving along both XY diagonals. 

Proper connection of the heated bed and the hotend

The selftest can determine a fault during the heating of a component, and the affected component. 

Heat up the affected component under LCD Menu -> Control -> Temperature, and see if any error appears. If it does, the error should have a QR code that redirects to the article that describes how to troubleshoot that particular error. 

Loadcell test

A functioning loadcell is fundamental for the Prusa CORE One to detect that the nozzle is close enough to the steel sheet for printing, and to avoid damage that would be caused by the nozzle digging into the steel sheet. 

• Make sure that the loadcell is correctly connected to the LoveBoard. 
• Make sure that the surface the printer is on is as stable as possible: any form of vibration propagated to the surface under the printer, or a not fully stable surface under the printer, might cause a false reading on the loadcell, causing it to fail the selftest. 

Filament sensor

The Prusa CORE One is equipped with two filament sensors: the first one is located on the side, close to the input of the PTFE tube where you feed the filament. The second one is located in the Nextruder.

Both filament sensors are necessary for the correct filament retraction. When the sensor on the side detects that the filament has run out, the filament will be retracted in time. 

• Make sure that the extruder filament sensor is correctly connected to the LoveBoard.
• Make sure that the side filament sensor is correctly connected.