Marlin Heating Failed: 3D Printer Firmware Issues.

You might be considering installing Marlin 2.0 in your 3D printer. However, you might be skeptical because of the problems associated with using the Firmware. Marlin is a very efficient open-source firmware. So what causes Marlin Heating Failed issue?

A Marlin “heating failed” issue arises when the thermistor has a problem. A thermistor regulates the temperatures of the 3D printer. The rise in temperatures will cause the print to fail. Another reason might be a thermal runaway, wrong setup, and code issues. A thermal runaway error alarm protects the printer from heating issues. It detects the heating failure and makes some sound which might be annoying.

Knowing the causes of the Marlin heating failed issue will help you detect the problem forehand. You can tell which behavior is related to what point and how to fix the error. Follow this guide for tips you can use to protect your 3D printer from overheating.

What causes the marlin heating failed issue?

Marlin heating failed to occur in two scenarios. The first reason is when the 3D printer reads MINTEMP. This issue occurs when the nozzle or the 3D printer bed cannot achieve the required temperatures.

The second reason that might cause an error in heating is thermal runaway. This happens when the 3D printer registers temperatures higher than the settings handle. All Marlin firmware, including

Each of the two scenarios: Thermal runaway and MINTEMP  issues, will be discussed in-depth. By the end, you will learn how to troubleshoot the problems with your 3D printer and fix them.


Mintemp occurs when the temperatures of either the hotend thermistor or heatbed thermistor drop below the required range over a period. The installed Firmware detects a defective thermistor and shuts off any heat from reaching the hotend of the heatbed. MINTEMP is a safety feature that prevents your 3D printer from overheating.

Different 3D printers trigger the MINTEMP  error featured at different temperatures. The feature in each 3D printer was set after a lot of tests. Adjusting the range might cause a fire or permanently damage the printer.

The table below shows the temperature range in which Marlin firmware displays MINTEMP in different 3D printers.

Printer modelHotend ThermistorHeatbed Thermistor
Mk2/S, Mk2.5/S22°c10°c
MK3, MK3S, MK3S+10°c10°c

For the MK 3D printer series, as seen in the table above, MINTEMP is triggered between 10°c and 22°c. Other quality printers in the market can experience this issue when the temperatures drop by 2°c for every 20second. 

MINTEMP error feature in 3D printer aims at;

  • We limit the printer from running if the thermistor cannot control the printer’s temperature.
  • They are preventing thermal runaway.
  • I stop printing if the printer cannot attain the required temperatures.

As discussed, your 3D printer can register MINTEMP in case of a defective thermistor. In other cases, a MINTEMP error might happen if you print in a cold room. We will discuss each of the two scenarios and how you can fix the issue to continue printing.

Room Temperatures

If the temperatures of the printing room are too low, the printer might start losing heat too fast. The printer’s temperature might drop until the thermistor cannot detect the temperatures. This results in a MINTEMP error signal.

Marlin 109 firmware regulates printing by using temperature stability. So if you are printing in a cold room, and the printer cannot balance the temperature of the room and that of the printer, the Firmware shuts off printing and display a MINTEMP error.

The solution to a cold printing room

  • Preheat the printing room up to temperatures slightly higher than the room temperature.
  • Place the printer in an insulated box before you start printing.
  • Keep adjusting the Watch_ Temp_ Period to see if the error will stop.

If Marlin firmware still displays a MINTEMP error, your thermistor might have a problem.

Defective Thermistor

A thermistor is a device that detects temperature change in a 3D printer and regulates the temperatures to the required range. Thermistors are usually attached to the nozzles cartridge or the hotend. This is because the two parts are dependent on temperatures when printing.

In the case of a loose, defective, or broken thermistor, the temperature does not balance as required. This might cause a MINTEMP error or a thermal runaway issue. For example, a broken or loose thermistor will allow air from outside into the printer. It might make the hotend to keep heating, to balance the temperatures between the printing room and the printer. This might lead to  Marlin firmware displaying a MINTEMP error.

The solution to a defective thermistor

Problems with the thermistor can be solved very quickly.

  • Check both the hotend and heatbed thermistors if loose.
  • A defective thermistor cannot fulfill its purpose. It would help if you, therefore, replaced a defective thermistor with one compatible with your 3D printer parts. Standard thermistors are compatible with an Ender 3 costs around $15.
  • Check the PID Values. If the values do not work well for your 3D printer, you can use Marlin M303 to auto-tune the values.
  • If auto-tuning fails, you can adjust the BANG_MAX parameters to fit your 3D printer.
  • Check the D-term/I-term ratio and adjust it to 4/1.5/25.
  • After all, the adjustments, restart your 3D printer and check if it’s working as expected.

A defective thermistor might also cause a thermal runaway issue.

Thermal runaway issue and protection

Thermal runaway describes a process where a slight increase in temperature leads to a release of energy that increases the temperatures even further. 3D printers are among the commonly affected electronics by this issue. It happens when the printer cannot stop heating up.

Thermal runaway in 3D printers might be caused by either a defective thermistor or the wrong setup.

  • Defective thermistor: If a thermistor cannot control the printer’s temperatures, it might cause your 3D printer to overheat and possibly cause a fire.
  • Wrong setup: you might have installed the 3D components in a way that reverses the chemical process causing the printer to overheat.

Does ender 3 and V2 have thermal runaway protection? Despite their affordability, ender three and ender 3 pro lacks thermal runaway protection feature. As a result, these printers tend to overheat and jam when you start printing.

To prevent your ender 3 from suffering from thermal runaway, install Marlin firmware.

As an open-source, Marlin firmware has a lot of advancements. One of the advancements is the thermal runaway protection feature. This feature detects the rise in temperatures beyond the setpoint, switches off printing, and reads “Thermal runaway” issues.

V2 3D printers have always had thermal runaway protection.

If Marlin still shows a thermal runaway error, use the following steps to fix the issue.

The solution for Marlin Thermal runaway error

  • Check the setpoints: A thermal runaway issue might arise if your 3D printer is printing with temperatures higher than the required temperatures. Always be on the range to avoid overheating your printer.
  • Check if the wiring and the assembly of the components are done properly.
    The thermistor and the cartridge should be placed in the center of the heat block.
  • Tighten and replace broken and defective thermistors.

Regularly maintain your Ender 3 by watching all the layers print.

Frequently Asked Questions (FAQs)

  • Should I turn off the thermal runaway protection feature?
    Thermal runaway protection is a very important feature. It detects a rise in temperature beyond the setpoint and switches off printing.
    If the rise in temperatures is not detected, it might damage the 3D printer and even cause a fire. Therefore, the thermal runaway protection feature should always be on during printing.
  • Can a 3D printer cause a fire?
    If the temperatures rise beyond the setpoint, the parts of the 3D printer might start to overheat and even explode.
    You should always leave the thermal runaway protection feature on during printing. This will help detect an increase in temperatures.
  • What is the purpose of a thermistor in a 3D printer?
    A thermistor detects an increase or decrease in temperatures in a 3D printer during printing. It is also responsible for regulating the printing temperature.
  • Where do I buy Marlin firmware?
    Most 3D printers come with installed Firmware. There is various Firmware in the 3D printing industry. Marlin is one of the commonly used Firmware. It has unique features like the thermal runaway protection feature and MINTEMP error.
    You can download the Firmware from the Marlin website or GitHub.


Marlin firmware is one of the most advanced Firmware in the 3D printing industry. It can detect if your 3D printer is facing a heating failure. Marlin Heating failed issue can be solved or detected early.

The open-source Firmware can detect an increase in temperature beyond the setpoint and switch off printing. It can also see when the temperatures are lower than the setpoint.

If your Ender 3 printer does not come with an installed Marlin firmware, you can download it from the Marlin website and install it. If you are experienced in the 3D printing industry, do not set up the 3D yourself. 


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