Bed Not Heating
Anycubic 3D Printer (FDM)
Severity:What Does This Error Mean?
The heated bed not warming up is usually a loose wiring connection, a blown thermistor, or a failed MOSFET. Check the wiring at the bed and the mainboard first before replacing parts.
Affected Models
- Anycubic Kobra 2
- Anycubic Kobra 2 Pro
- Anycubic Kobra 2 Max
- Anycubic Kobra 2 Neo
- Anycubic Kobra Neo
Common Causes
- Loose or broken wire at the bed connector
- Bed thermistor failed — printer cannot read bed temperature
- MOSFET on the mainboard burned out
- Firmware thermal protection triggered by a faulty thermistor reading
- Bed heater element physically damaged
How to Fix It
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Check the bed wiring connector at the back of the printer.
The bed has two sets of wires: the heater wires (thicker) and the thermistor wires (thin). Inspect both connectors where they plug into the mainboard. Reseat any loose connectors.
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Monitor the bed temperature reading on the screen.
If the screen shows 'E' or an obviously wrong temperature (0°C or 300°C), the thermistor is the problem. A working bed thermistor reads room temperature at startup.
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Replace the bed thermistor if the reading is wrong.
Anycubic Kobra uses a standard NTC 100K thermistor (B3950). They are inexpensive. Insert the new thermistor into the bed's thermistor hole and secure it with thermal tape.
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If the thermistor reads correctly but the bed does not heat, the MOSFET may be faulty.
This requires mainboard replacement or a dedicated external MOSFET module. Contact Anycubic support if your printer is under warranty — they often send replacement boards.
Frequently Asked Questions
Does the Anycubic Kobra need a heated bed for PLA?
Technically no — PLA can print without a heated bed. But 55-60°C bed temp significantly improves first layer adhesion and reduces warping, especially for large prints.
Is a failing bed MOSFET dangerous?
A burned MOSFET can overheat. If you smell burning plastic from the mainboard area, stop printing immediately. Do not leave a printer with a suspect MOSFET unattended.