Thermal Runaway


Staff member
What is a Thermal Runaway?

A Thermal Runaway is an error that occurs when the temperature on your hotend or heated bed has dropped below the expected temperature for over a certain amount of time. If this error occurs, that means there is a problem with either the Thermistor, Heater Cartridge, or improper wire connections (Ribbon Cable, Hotend power wire, etc).

E1 Thermal Runaway.gif

What are the parameters needed to trigger a thermal runaway?
Thermal runaways need to hit certain circumstances in order to trigger. These are embedded in the Marlin Software as a safety feature and cannot be edited.
For the Extruder: The Hotend has to drop below 6ºC of the target temperature in order to trigger the "thermal runaway counter". If the temperature doesn't rise back up to the target temperature (within a 6ºC tolerance) within 40 seconds, the printer will prompt an E1 Thermal Runaway.

Where is the Thermal Runaway occurring:
E1 Thermal Runaway= Extruder 1
E2 Thermal Runaway = Extruder 2
Bed Thermal Runaway = Heated Bed

Possible Quick Fixes:
• You can try preheating your gMax to PLA temperatures and wiggle the ribbon cables while it is temping up. If you notice a sudden loss of temperature increase due to the wiggling, then your ribbon cable needs replacing.

• You can purchase a new Heater Cartridge from our website:

If you'd like to find out more information, you can use the link below to go to Marlin's troubleshooting website: