There is nothing more frustrating than a “printer halted” error message on an Ender 3. When that message is accompanied by “thermal runaway,” things can get downright scary.
What is a thermal runaway, anyway?
Ender 3 thermal runaway is among the most dangerous errors in 3D printing. This message tells you that the printer can’t stop heating up. The operation is stopped to prevent printer damage or starting a fire. Thermal runaway can affect all Creality Ender 3 printers, including the V2 and Pro.
What Is Thermal Runaway On An Ender 3?
Ender 3 thermal runaway is a malfunction of the 3D printer that causes an accelerated increase in temperature.
The malfunction can be caused by either the hardware or software; regardless of its cause, the printer can’t stop heating up once it goes into a thermal runaway – hence, the error name.
Given that the normal printing temperature is between 428°F and 464°F, it is easy to understand how the Ender 3 can reach extremely high temperatures fast.
If left unattended, thermal runaway can lead to permanent damage to your printer and even set your house on fire.
The standard message on the control screen is Thermal Runaway. Printer Halted. Please Reset.
Thermal runaway is commonly caused by a faulty thermistor or heating cartridge disconnected from the heating block.
An old, faulty, or disabled firmware may also lead to this issue. Other hardware problems or a worn-out printing bed could also be the cause.
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9 Possible Causes Of Thermal Runaway On An Ender 3
The Ender 3 thermal runaway please reset message can make you feel doomed.
However, this error doesn’t always signal a major issue. Sometimes, all you have to do is to enable the temperature control on the firmware.
Below are the most common thermal runaway causes.
1. Faulty Thermistor
The first thing to check is the thermistor when your Ender 3 Pro or V2 firmware stops the printer and displays the above error message.
This component located under the heated bed controls the temperature of the heated bed and the nozzle.
Not only is it responsible for creating successful prints, but a faulty thermistor can start an Ender 3 fire if it can’t stop the heating elements once a certain temperature is reached.
Thermal runaway aside, the thermistor is also responsible for other common error messages, such as heating failed printer halted.
When either of these errors come up, the thermistor is either disconnected or needs to be replaced.
Fortunately, replacement thermistors are easily found on the market, and you might be able to replace this part on your own.
2. Silicone Cover Not Attached
3D printers, including Creality’s Ender 3 V2 and Pro, come with a silicone sock that goes over the hotend.
This cover helps the hotend heat to the desired temperature faster, but inexperienced Ender 3 users might believe it’s optional and are tempted to remove it.
While this cover retains heat, it was observed that taking it off could cause the printer to register a hotter temperature and go into thermal runaway error.
The good thing is that all you have to do is slide the silicone sleeve back on to fix the problem.
3. Faulty Wiring Work
If the thermal runaway error pops up after the printer starts moving, the wire loom is a possible culprit.
All loom wires are subject to bending and flexing as the printing head moves, and two wires could touch the thermocouple at the same time, or they could come loose.
The heater wires may also be misconnected or loose.
Check the connection and test the printer by connecting a temporary line from the sensor to the board. If the error doesn’t show up, you must rewire the wire loom.
Otherwise, check the heater wires and rewire them if necessary.
4. Extruder Issues
A common printing mistake that could cause your V2 or Pro Ender 3 to go into thermal runaway is starting a new print without giving the extruder time to cool down.
When starting a new print while the extruder is still hot, the thermistor could interpret it as a temperature shot-up.
To fix this issue, let the printer cool down completely before starting a new print.
5. Nozzle Hotter Than Expected
Alongside the extruder, a hot nozzle could also be responsible for your printer going into thermal runaway.
Again, this is a user error that can be avoided. Simply let the printer cool off before starting another print.
6. Worn-Out PEI Bed
When printing objects, you may be tempted to place them in the center of the bed. However, repetitive printing in the same spot can cause the PEI bed to wear out.
The thermistor is typically located under the center of the bed. If the PEI is worn out, the thermistor could register a higher temperature due to the proximity to the hot nozzle and printing material.
To prevent premature wearing out of the PEI bed and thermal runaway errors, avoid choosing the same spot for your prints, especially if they are small pieces.
7. Faulty Thermocouple
The thermocouple is a device placed on the nozzle. It is responsible for transmitting the temperature to the firmware. If it registers a temperature higher than that set by the firmware, the printer will go into a thermal runaway error.
Loose wires or wrong connections are common culprits. A faulty thermocouple amplifier could also cause this problem.
8. Faulty/Outdated Firmware
One of the main issues with most Ender 3 printers is the type of firmware they come with. These entry-level printers can have firmware that isn’t calibrated correctly, or that is outdated.
Check the firmware and adjust the temperature range or recalibrate if necessary.
Wrong calibration or incorrectly set temperature range could also be responsible for Ender 3 bed not heating, or Ender 3 heating failed errors.
9. Disabled Firmware
Before running a calibration or resetting the temperature range, check the firmware and make sure the temperature control is enabled.
If this setting is disabled, the printer won’t stop the heating when the printing head or bed reaches the set temperature. This can lead to overheating, which will lead to thermal runaway in return.
How To Fix Thermal Runaway in Ender 3 (V2/Pro)
The only way to fix thermal runaway is by running a diagnosis on your Ender 3 printer.
Start with the thermistor and check the wires. Connect them if loose.
Move on to the wire loom and also check out the other connections. If the wiring seems fine, check the thermocouple and PEI bed.
If you can’t find any hardware issues, check the firmware and update, calibrate, or set the parameters again if necessary. Don’t forget to let the printer cool off completely before starting a new print.
If nothing works, you might have to replace the thermistor.
How To Prevent Thermal Runaway On Your Ender 3
Preventing is always better than fixing. If you don’t want to run into troubles later – and deal with thermal runaway errors – do the following things periodically.
Update Your Firmware
As explained above, your Ender 3’s firmware might be responsible for the thermal runaway problem.
Even if you’ve fixed the temperature issue, you should still update the firmware periodically. Keeping it up to date is a must for enhancing security and safety.
Enabling Thermal Runaway Protection
Thermal runaway protection (TRA) is an important safety feature. When enabled, it can prevent unexpected thermal runaway-related incidents.
When setting up your Ender 3 for the first time or updating its firmware, don’t just assume this option is checked.
While TRA should be enabled by default, there were reported incidents when the setting got disabled after an update. Check the settings if you’re unsure and tick to enable it if necessary.
Maintenance
In addition to checking the TRA setting, creating a maintenance schedule for your 3D printer is crucial.
Checking for loose connections and cleaning the nozzles should be done at least once a month or sooner if you print a lot. Also, control other parts of the unit, such as the heat block, silicone cover, and PEI bed.
Let The Printer Cool Down
A reason for thermal runaway error is starting a new print before the bed, nozzle, and extruder are completely cooled down to room temperature.
If they are still hot, the printer could interpret it as a fast rise in temperature and cease operation to prevent overheating or setting anything on fire.
Tips To Minimize Fire Hazards With Ender 3
Checking your printer regularly, updating the firmware, and making sure all settings are correct and that everything is in good working order can only help so much.
If an accident happens, here are some ways to minimize fire hazards.
Keep Your Workspace Clean
Ender 3 printers – much like all other 3D printers – rely on heat to melt the spool and create your 3D objects. Whether you get a thermal runaway error or not, these machines can sometimes overheat.
Keeping your workspace clean and organized can help you prevent accidents.
As a rule of thumb, you should never keep blueprints, diagrams, notebooks, or other paper materials near the printer. Also, avoid leaving stuff like solvents or other flammable materials open around the machine.
Store Flammable Materials Away From Printer
Keeping the workspace organized may not be enough, especially if you want to leave the printer to do its job unsupervised.
If you have to store any flammable materials in the same room as the Ender 3, place them in a closed cabinet as far away from the printer as possible. Preferably, you should keep them in a metal cabinet.
Set A Cooler Room Temperature
Entry-level 3D printers are more prone to overheating compared to high-end models. This is true for most Creality printers, including Ender 3 Pro and V2.
To minimize the overheating risk, set the room temperature at 77°F or lower.
Ensure Airflow
Setting up your 3D printing studio in a room with windows is ideal, but you should still ensure airflow even if the room is windowless.
Install an extractor fan and air conditioning (or a freestanding fan) to move the air as much as possible.
Invest In Fire Extinguishers
A fire extinguisher can save the day if your printer catches fire. You should have a can right next to the printer and at least another one or two in the room.
Install A Smoke Detector
Another safety measure if you want to leave the printer work unsupervised is to install smoke detectors.
These life saving devices can alert you if something goes wrong and even start a sprinkler system to put out the fire.
Install Tile Floors And Use Metal Furniture
If possible, set the 3D printer in a room with tile or concrete floors and replace any MDF or hardwood furniture with metal alternatives.
These materials aren’t flammable and will make it easier to contain the fire if needed.
Conclusion
Ender 3 thermal runaway is a serious error that could signal extreme overheating. This error can also come up due to loose wires, hot nozzles or extruders at the beginning of the printing cycle, or firmware issues.
Most problems are easy to fix. However, if you’re unsure, call the Creality service center or an expert. If the printer reaches extreme temperatures, it could set your house on fire.
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