MINTEMP & MINTEMP BED

Updated 1 day ago ​by Tomáš Chvalina

The MINTEMP error occurs when the temperature readout from the heatbed thermistor or from the hotend thermistor drops below 16°C. It is a safety feature that prevents the printer from overheating in case of a faulty thermistor, because by default, the printer is set to balance out any heat loss by pumping more power into the heatbed or hotend heater cartridge.

What does it look like?

It is important to distinguish between the MINTEMP error and the MINTEMP BED error.

MINTEMP - problem with the hotend temperature readout

MINTEMP BED - problem with the heatbed temperature readout

This error can be caused by a simple glitch or a breeze. Starting from firmware 3.7.1, the printer is able to recognize it and fix the MINTEMP by itself. If the LCD displays "MINTEMP fixed" message, just restart the printer by pressing the X button under the knob.

How to fix it

For pre-assembled printer owners: If you happen to receive the printer during the winter and you want to start using it out of the box, wait until it reaches room temperature. 
Temperature

Make sure that the temperature of the room where you operate the printer is not below 20°C. Also make sure the printer is not placed next to an opened window, air conditioning or in a way of a breeze that might cause a sudden temperature fluctuation.

Glitch

As mentioned above, the error might have been caused by a simple glitch. Try to reset your printer by pressing the X button under the knob and see if it will print afterwards.

Thermistor connection

Check if the thermistor is properly plugged into the RAMBo board. If your printer model is MK2, MK2S, MK2.5 or MK2.5S printer, check this page, if it is MK3 or MK3S, check this page.

  • Look for any damage on the thermistor cable, especially where it enters the RAMBo case and where it is inserted into the heater block and heatbed cable cover.
In case there is a visible damage on the cable, the thermistor must be replaced.
  • Electronics board thermistor input is broken. Highly unlikely, as the board would fail to pass the final testing on our test bench. If only one temperature readout shows 0°C. Try switching the Hotend and Heatbed thermistors on the board, if the faulty readout remains the same, the electronics board is broken. New board is needed.
  1. If the issue persists or you are not able to find the source of it. Then you can perform a simple test described below, which tests the thermistor readings.
  2. You can also test it with a multimeter, if it fails to read the resistance (infinite resistance), then the leads are broken and the thermistor must be replaced (Semitec 100kOhm NTC Thermistor. 104GT-2).

MINTEMP BED

  1. Make sure that the ambient temperature is not below 16°C.
  2. The error might have been caused by a simple glitch, so try to reset your printer with the reset button and see if it is possible to operate it normally afterward. 
  3. Check that the thermistor is plugged correctly into the electronics board. You can doublecheck that by following the MK2/MK2S Electronics Wiring or MK3 EINSY miniRAMBo electronics wiring guides.
  4. Make sure that the heatbed thermistor is firmly attached to the underside of the heated bed with the golden Kapton tape. If not, then simply put it back and make sure that the thermistor cable has some space for movement.
  5. The thermistor cable might be wearing down. This can be observed if the temperature starts randomly jumping up and down during the Y-axis movement. Look for any overtightened zip-ties around the cables leading to the electronics board. In the case of a broken thermistor cable, the thermistor must be soldered or replaced.
  6. Electronics board thermistor input is broken. Highly unlikely, as the board would fail to pass the final testing on our test bench. If only one temperature readout shows 0°C. Try switching the Hotend and Heatbed thermistors on the board, if the faulty readout remains the same, the electronics board is broken. New board is needed.
  7. If the issue persists or you are not able to find the source of it. Then you can perform a simple test described below, which tests the thermistor readings.

  • It should have a resistance of ~100kOhm at room temperature. Maybe you are not in the correct range?

Can you please measure the resistance of your thermistor following this guide: https://help.prusa3d.com/article/mvzxcjkvtx-troubleshooting-multimeter-usage


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