Selftest (MK3 and MK3S)

Updated 8 hours ago ​by Tomáš Chvalina

The first thing you need to do after assembling your printer is running the Selftest. This routine looks for the most common problems in the build quality and electronics wiring. The Selftest prompt appears automatically on the screen once you turn on the printer for the first time. To start the Wizard, select [yes] by pressing the knob. You can manually start the Wizard at any time from LCD Menu - Calibration - Wizard.

This procedure should not be necessary for pre-assembled printers.
After the initial calibration, the Selftest can be found in LCD Menu -> Calibration -> Selftest .

The Selftest procedure checks the following:

  1. Extruder and print fan functionality
  2. Heatbed and hotend wiring
  3. XYZ motors wiring and functionality
  4. XY axis length
  5. XY belts tension
  6. Loose belt pulley 
  7. Filament sensor / IR sensor

Progress and result of each step are displayed on the LCD screen. In case the process runs into an issue, the LCD screen will display an error message. All errors are described below.

Selftest error messages

Extruder & Print fan test

Front print fan/Left hotend fan - Not spinning:

The MK3 Selftest procedure is capable of telling you which of the fans doesn't work. Simply check the one that is diagnosed as not OK.

  1. Make sure that both of your fans are connected properly to the EINSY miniRAMBo board.
  2. Check for any blockage that could prevent either of the fans from spinning. 
  3. Go over the wiring and make sure that none of the zip-ties is overtightened, which prevents the fans from spinning.

Heatbed & Hotend test

Please check/ Not connected - Heater/ Thermistor:

Bed/ Heater - Wiring error:

  1. Make sure that both thermistors and heater are connected properly according to the EINSY miniRAMBo board guide.
  2. Check your heated bed cables and confirm they are not damaged by an overtightened zip-tie. 
  3. Make sure that your heated bed thermistor is firmly attached underneath the Golden Kapton tape.

XY axis length test

Please check: Axis length - Axis {XYZ}: 

  1. Start the Selftest routine again in LCD Menu - Calibration - Selftest. Carefully observe, whether no obstacles are blocking the path on any of the axis.
  2. Pay attention to extruder cable management and the assembly of the printer's axes. The most common cause of an improper X-axis movement is the cable harness hitting the EINSY Mini RAMBo cover.

Loose belt pulley test

Loose pulley - {XY}:

  1. Make sure that both pulleys are properly tightened. If any of them is loose, then the motor's shaft won't be able to move the axis.
  2. Make sure that the belts aren't extremely loose, as they might be going around the pulleys without actually moving either of the axes.

Filament sensor test

Filament sensor wiring error

  1. Make sure that the filament sensor is correctly connected to the connector.
  2. Make sure that the filament sensor is correctly plugged into the MK3 EINSY miniRAMBo electronics wiring.


Find out more troubleshooting tips here: Community Forum | Assembly Manuals | Youtube channel |

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