Selftest failed (MK2/S, MK2.5, MK2.5S)

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The first thing you need to do after assembling your printer is running the Selftest procedure. This routine checks for the most common issues 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 the LCD Menu - Calibration - Wizard.

Selftest procedure checks

1. Extruder and print fan functionality
2. Heatbed and hotend wiring
3. XYZ motors wiring and functionality
4. XYZ endstop mechanical settings and wiring axis length
5. Loose belt pulley test

Both progress and result of each step are displayed on the LCD screen. If the self-test process runs into an issue, the LCD screen will display a corresponding error message. All errors are described below.

Self-test error messages (MK2/S)

Extruder & Print fan test

Front print fan/ Left hotend fan - Not spinning:

1. Make sure that both of your fans are correctly connected, as described in the Mini RAMBo electronics wiring (MK2S, MK2.5, MK2.5S).
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 over-tightened, 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 Mini RAMBo electronics wiring (MK2S, MK2.5, MK2.5S).
2. Check if your heated bed cables are not damaged by an overtightened zip-tie. 
3. Investigate your Heated bed thermistor. It must be perfectly attached underneath the Golden Kapton tape.

XYZ endstop & motor test

1. Once this error is triggered, it means that either X/Y end stops or X/Y motors were not properly plugged in the mini RAMBo board. 
2. Check the Mini RAMBo electronics wiring (MK2S, MK2.5, MK2.5S) guide and move them to their proper position.

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 your belt isn't extremely loose, as it might be just going around the pulley without actually moving either of the axes.