E1 MaxTemp Error

What is Thermal Runaway Protection? #

Thermal Runaway Protection is enabled in all Unified Firmware releases for all printers. This feature prevents the printer from operating when there is an issue with a heater or thermistor. Thermal Runaway errors occur when a thermistor fails to report a temperature properly, when a heater overshoots its target temperature or heats while it should be idle, or when a thermistor fails to register an increase in temperature when attempting to heat that device. In these cases, the firmware should present an error message and then immediately attempt to cut power to all functions of the printer, which prevents overheating, damage, and possible fire.

Thermal Runaway errors may NOT be able to control external devices that have their own power supplies or control units. When you encounter a Thermal Runaway error, you should ensure that you completely power down the printer and any additional devices or accessories attached to it.

E1 MaxTemp Error – Printer Halted #

The E1 MaxTemp error indicates that there is an issue with the “E1” device, which would be “Extruder 1” or the main hot-end on most 3D printers. An E2 error would indicate an issue on a second extruder/hot-end, and the bed has its own error as well. Typical causes of these errors include:

  1. Thermistor wire is pinched, damaged, unplugged, not fully seated, etc.
  2. Heater cartridge wire is pinched, damaged, unplugged, not fully inserted into the screw terminal, plugged into the wrong terminal, etc.
  3. Bed heater wire is pinched, damaged, de-soldered, unplugged, not fully inserted into the terminal, plugged into the wrong terminal, etc.
  4. Mainboard damage, including shorts to screw terminals, faulty wiring, blown components, incorrect wire configuration or polarity, etc.

The E1 MaxTemp error IS NOT a problem with the firmware itself in most cases. This instance is the firmware correctly displaying an error when there is a potentially dangerous situation, hence it is operating as intended. Once an error occurs, the printer must be reset by completely powering down the printer then powering it back on.

What do I do if this error occurs? #

  1. Unplug the printer and associated devices from power. This includes any other ancillary items, such as MOSFETS, SSRs, any third-party or external components that have separate power supplies or cables, etc. The printer and ALL accessories should be powered off and disconnected.
  2. Allow everything to cool before handling. Components may be hot, even if the error occurred while the printer was idle. Make sure to leave time for everything to cool while disconnected from power.
  3. Completely and thoroughly inspect ALL printer components, with an emphasis on the heaters and thermistors, their wiring, and their connectors. Check for any pinched or damaged wires, check for any loose or improper connections to the mainboard, check for any damaged components.
  4. Thoroughly examine the printer’s mainboard for damaged components, destroyed terminals, or any signs of an electrical short. The mainboard can also be the cause of the issue if there are electrical shorts, failed components, or improper installation.
  5. Depending on what component is causing the issue, you may consider replacing that component with a new one. Assuming nothing else on the printer is damaged, you can replace hot-end components as needed. If you can determine the cause of the problem, you can also ensure that the issue is corrected so that it does not occur repeatedly.
  6. If you are using a brand-new printer that is still under warranty, contact the manufacturer about exercising that warranty. Thermal Runaway errors SHOULD NOT occur on brand-new hardware from the factory. If you encounter this error while the printer is under warranty and still using stock components, immediately discontinue use and contact the manufacturer.
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