The Marlin firmware has some security functions to protect against fire. When the heating bed and the nozzle are warmed up, a constant check is carried out to determine whether the defined temperature increase has been reached within a defined time window. If a sufficient temperature increase is not reported, e.g. due to a defective sensor, the printer is stopped and the heating process is ended. 

The error can also appear suddenly during printing.

With the Weedo 1.2.0 / 1.2.1 firmware, the default values are incorrectly defined in the firmware. Since the heating bed very slowly reaches its final temperature at high temperatures, the wrong settings will trigger the error, although there is no defect.

With a correct configuration as with the X40 PRO Firmware, the error only occurs if the nozzle and the heating bed are very hot, the printing is aborted and immediately restarted. If the error occurs when warming up, there may be a defect in the sensor, the heating cartridge or the heating bed.

If the error does not occur during the warm-up phase but during printing, then this may be due to a loose temperature sensor and/or heating cartridge. A cable break from the hotend or bed temperature sensor or the heating element is also possible. In addition, incorrect PID settings can also cause the error.

With the Weedo firmware you can partially work around the error by manually preheating the printer.

If the error occurs with the X40 PRO Firmware, then there may be a defect. If the printer generates the error again after a restart, check the sensor, the heating cartridge and the heating bed. Even with the X40 PRO firmware, the error cannot be ruled out 100%, but it occurs much less often than with the Weedo firmware.

If the error occurs during printing, then check whether the temperature sensor and the heating element are firmly attached. If necessary, perform a PID tune and store the data in the EEPROM or Cura startcode.

Nozzle failure: temperature can't be read 

(Mintemp error)

Nozzle failure: temperature exceeds maximum 

(Maxtemp error)

Printer selftest
LH/RH Nozzle Heating Failed

The cause can be very diverse.

• One or more plug connections may have come loose
• The heater cartridge and/or the sensor may not be properly attached to the heater block
• There may be a defect in the heating cartridge or the sensor. There are several users with a burnt out cartridge heater. The error is not that rare.
• There may be a broken wire 
• An incorrect cartridge heater or sensor may have been installed  

• Check the plug connection to the mainboard in the control panel
• Check the attachment and seating of the heating cartridge and the sensor on the heating block. Often the screw and washer has come loose from the sensor and the sensor has no contact with the heater block
• To check if the cartridge heater is working, remove the insulation around the heater block. During the printer self-test, pick up the heating block and check whether it heats up. If not, then the heater cartridge is probably defective. If the heating takes place, but the error still occurs, then the sensor is defective  

The cause can be very diverse. 

• One or more plug connections may have come loose
• The heating bed and/or sensor may be defective

• Check the plug connection to the mainboard in the control panel 

The cause can be very diverse.  

• One or more plug connections may have come loose
• The switch is loose or not in the correct position
• The print bed or print head does not move to the switch.
• The switch is defective
• The motor is defective
• The belt is not transmitting motion to the table or printhead because the belt has come off, broken, or the pulley is loose

• Check the plug connection to the mainboard from the switches
  
• If the print bed or print head does not move, then check the plug connection of the motors and the belt
• Disable the self-test and checked the movement of the axes via the maintenance function

The cause can be very diverse.  

• There is no magnetic printing plate on the printing bed
• Sensor is set too high and the signal is not triggered
• The sensor plug connections may have come loose
• One or both Z-motor cables have come loose
• The Z-spindle clutch has come loose
• The Z spindle is stuck and cannot rotate
• The sensor is defective
• The z-motor is defective

• Check the function of the sensor by holding something magnetic under the sensor. If the LED lights up, then switching is working
• Check if the sensor is adjusted correctly (see Set the Z-Level and Bed Level correctly)
• Check the plug connection to the mainboard from the proximity sensor
  
• If the print bed or print head does not move, then check the plug connection of the motors and the belt
• Disable the self-test and checked the movement of the axes via the service function

The printer can use a small microswitch to determine whether filament is present if the function is activated in the menu. The function of the switch is not checked during the self-test. A defective switch can therefore only be recognized in the event of a malfunction. 

The printer does not stop even though there is no filament. 

The cause can be very diverse. 

• The runout sensor was not activated in the printer menu
• The cable from the switch has come loose
• The small plastic button nose on the switch has broken off or the switch is defective

• Check in the menu if the runout sensor is active 
• Check the cable connection from the runout sensor to the mainboard.
• Disassemble the extruder and use a gauge and a piece of filament to check if the microswitch works. Most of the time, the small nose is torn off the microswitch and the switch is no longer pressed.

Black screen, the printer went off while printing. 

After switching on, the typical error message for a power failure is displayed

Possible cause when printing via MicroSD card:

• A cable has come loose or there is a loose contact
• The power supply is defective and turns itself off as a precaution against a band
• There is a broken cable

Possible cause when printing via OctoPrint:

• You forgot to deactivate the automatic switch-off on the printer
• You unknowingly inserted an M81 command into the gcode
• There is an error such as when printing via the MicroSD card

• Deactivate the Autopower off function on the printer. Repeat the canceled print and print from the MicroSD card. If the printer goes out again while printing, disconnect the printer from the power supply and open the control panel from below. Check that all cables are properly attached, especially the power supply. If there is a noise in the power supply unit or even a flash when the printer is switched on, this is a typical sign of a defective power supply unit. 

The filament sensor is active and the printer stops during printing.

The printer is waiting for the filament to be inserted and for confirmation to continue printing. 

The filament sensor has been triggered, this can be due to the following reasons: 

• Filament is broken and the break is not visible
• Plug connection from the filament sensor has come loose or there is a loose contact
• The filament sensor switch is defective

• Check the plug connection from the filament sensor
• Carefully open the flap over the filament sensor on the extruder and check whether the switching lug is present and also protrudes into the guide channel.
• Disable the filament sensor and print the next prints without the sensor. If the problem still occurs, the sensor defect can be ruled out.

The printer stops at bed leveling.

Possible cause:

• The distance between the nozzle seat and the switching point of the sensor is set incorrectly.
• The bed is not aligned precisely enough.

• The proximity sensor is set correctly when the nozzle tip has a distance of 1mm to 2mm to the bed in the switching point.
  Have a look at "Set the Z-Level and Bed Level correctly" and adjust the proximity sensor.
• Do the bed leveling and set the Z offset

The WIFI module was disconected unexpect edly, printing was aborted.

The WLAN network connection is too bad or disrupted.

• Improve the wireless network quality by moving the printer closer to the router or installing a WLAN repeater
• Alternatively, you can also try a network connection via a Raspberry Pi with WLAN function and OctoPrint.