How to Fix Thermal Runaway Error on Your Anycubic 3D Printer

One of the most terrifying issues that could arise with 3D printing is thermal runaway. It might ignite a fire in your house in addition to harming your printer. In the context of 3D printers, thermal runaway refers to a situation in which a printer cannot stop heating up, frequently as a result of faulty or improperly fitted gear.

To fix a thermal runway error on your Anycubic, firstly make sure that the print is up-to-date on maintenance. Next, check the thermal runway protection mechanisms in the firmware of your Anycubic. Make sure to keep the environment where your Anycubic is placed as fire safe as possible. Lastly, if the thermistor is broken, you must replace it with another one.

In this article, we’ll discuss a few ways to keep your Anycubic from experiencing thermal runaway. Both hardware (physical) and firmware (online) options exist in these solutions. Let’s start by thinking about the state of your printer.

Common Solutions

Check Your Printer

Taking evasive action is the primary line of defense against thermal runaway on an Anycubic. Checking your printer is the simplest approach to prevent thermal runaway. This refers to performing routine maintenance on your printer to make sure all systems are stable, and it is operating properly.

Make that all of the instructions for assembling your Anycubic were properly followed, especially those pertaining to the wiring. Additionally, make sure your hot end’s thermistor and heating cartridge aren’t too far away from one side.

Related: Why Is My Anycubic Kobra Not Sticking to Bed? Answered

You should secure those two wires into place after making sure they are positioned properly. This entails tightening the thermistor and heating cartridge screws on the hot end’s bottom. By doing this, you can prevent your thermistor from escaping the heat block, which would probably result in thermal runaway.

You should maintain your printer in this condition in addition to making sure your Anycubic is correctly put together and nothing is broken. Everyone wants to get to the printing stage as soon as possible but performing the occasional maintenance check can keep you informed about your Anycubic’s functionality and help you avoid many issues in the future.

Watching the first layer of each print before it leaves the printer is a smart technique to make sure your printer is operating properly. It might be worthwhile to spend money on monitoring tools and software if you are unable to monitor the print or if your print will take a while.

Furthermore, vacuuming is always a good idea. Dust is extremely combustible and can lead to mechanical or electrical issues.


The thermal runaway protection mechanisms in your Anycubic firmware are the second fix. The firmware of your 3D printer enables the motors, sensors, and other parts of your device to communicate with one another.

A feature known as thermal runaway protection can identify when the printer’s heating system is malfunctioning. When the system determines that the goal temperature is too distant from the actual temperature, this program in the Anycubic firmware causes heating to halt. This is typically caused by a thermistor that is malfunctioning or in the wrong spot and isn’t detecting the temperature correctly.

Related: Best Cura Settings for Anycubic Mega X

Safe Environment

Maintaining a safe atmosphere for your printer is an effective preventative measure against thermal runaway. You’ve already taken steps to reduce the risk that your printer poses to the area around it. It’s time to make sure that your printer is not in danger from its surroundings or environment.

The most apparent precaution is to avoid putting any flammable substances – like acetone – near the hot end or the printer as a whole. Keep your desk organized and especially devoid of paper because fire needs fuel to start.

In order to avoid problems caused by high heat, like the controller board burning out, you must also make sure that the space where you keep your printer is not excessively warm. A room with some type of ventilation is also necessary for your printer’s setup. For the purpose of dispersing any fumes or smoke, airflow is extremely important.

On that note, it wouldn’t be a terrible idea to keep some fire safety equipment close to your Anycubic just in case. Installing a smoke detector will notify you of any fire indications. If the worst-case scenario happens, keeping a fire extinguisher close by is also a wise security precaution.

Replace Thermistor

Your problem may be rooted in a broken thermistor. In that case, it’s best to replace it.

Follow the below steps to safely replace the thermistor:

  • Make absolutely sure your Anycubic printer is powered off and not operating before continuing.
  • The fan shroud should be removed by unscrewing it.
  • Shorten the length of the zip ties keeping the wires in place. Use a little screwdriver to now detach the screw holding the thermistor in its proper position.
  • Remove the damaged thermistor, however, if it gets trapped, it is likely because molten plastic is keeping the thermistor inside. If you experience this problem, heat your hotend to about 185°C or 365°F so that the plastic can melt, extract it with a tool, and then allow your hotend to cool before trying again.
  • You ought to be able to carefully remove the thermistor after it has cooled down.
  • The plug end of the new thermistor should be inserted into the old thermistor wire and secured with tape because installing the new thermistor is a bit challenging. To correctly insert the thermistor, pull the precise wire back from the other side now.
  • The new thermistor should now be plugged in exactly where the previous one was.
  • Attach the zip ties to the wires again, check to make sure no wires are exposed, and that the thermistor is properly connected. The wires on the other end of the thermistor should now be inserted into the bottom hole and carefully screwed up.

How to Test for Thermal Runway?

It’s very to test for thermal runway. Using a hair dryer on your hotend for about a minute to lower the nozzle’s working temperature should be able to prompt the Thermal Runway error.

You can use a different technique if there isn’t a hairdryer around.

Another proper test When printing or while sending commands to the printer directly via USB to specify a temperature, you can disable the heater element of the hotend or the heated print bed to properly test the thermal runaway protection feature.

You can disconnect the heater element when the printer is shut off or even just starting to warm up.

Related: Anycubic Kobra Screen Goes Black? Fixed

The nozzle won’t be heated because the heater element has been disconnected. The printer should cease operations and will shut down if the thermal protection feature is activated after the temperature testing period and settings defined in the firmware.

It is advised to disconnect the printer first, then reconnect the wires, as doing so while the printer is on could result in you touching the exposed cables.

You must reboot or reset the printer if it stops functioning after displaying a thermal runaway error before you can begin printing.

If the printer continues to operate without stopping, immediately shut it down because this is an obvious indication that the thermal runaway prevention is not turned on.

Frequently Asked Questions

Why is the 3D Printer Extruder Not Heating Up?

If your extruder is not heating up, make sure that the appropriate extruder is chosen on each tab of the settings. Choose the left or right extruder from the top menu, then be sure to choose the primary extrusion on the first tab, the support extruder on the second tab, and the infill extruder on the third tab.

What Causes Overheating in Printers?

The plastic not being cooled down quickly enough is the most frequent reason for overheating. When this occurs, the hot plastic has free reign to assume various shapes as it gradually cools. It is much advisable to swiftly cool the layers for many plastics in order to prevent form changes after printing.

What Happens if You Print PLA Too Hot?

Stringing and blobs/oozing will occur when you print at an excessively high temperature (with any material, not only PLA), as a result of the filament being runny and erupting out the nozzle in an uncontrolled manner. You may also notice artifacts in your prints because it is unregulated.

What Causes Thermistor Failure?

These failures are typically brought on by handling damage, excessive heat, thermal mismatch, etc., which results in mechanical separation between the resistor element and the lead materials. The second most frequent failure cause is parameter change or drifts in resistance value as the thermistor ages.


A thermal runway error is a 3D printing enthusiast’s worst nightmare. Make sure to follow the preventive and remedial solutions discussed in this article to continue to safely print with your Anycubic.

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