P
12212
Moderate
Prusa · FDM 3D Printers
MAXTEMP Bed - Heated Bed Temperature Exceeds Safe Maximum
Quick Answer
Error code 12212 on your Prusa FDM 3D Printers means: MAXTEMP Bed - Heated Bed Temperature Exceeds Safe Maximum. This is usually fixable — see the step-by-step guide below.
Affected Models
Applies to all models
MINI+MK3.5MK3S+MK4MK4SXL
Likely Causes
  1. Bed thermistor short circuit reporting falsely low resistance
  2. Thermal paste or adhesive on thermistor has degraded causing poor thermal contact
  3. Moisture ingress into the thermistor connection under the bed
  4. Bed MOSFET stuck in the on state
How to Fix It
1
Power off the printer immediately
2
Inspect the bed thermistor mounting point on the underside of the heated bed
3
Measure thermistor resistance to check for short circuit condition
4
Inspect the mainboard for visual signs of MOSFET damage (burnt or discolored component)
5
Re-seat the thermistor with fresh thermal paste if the connection appears degraded
Pro Tip
This fix requires some technical knowledge. If you're unsure about any step, consider contacting support or a qualified technician.
Parts You May Need
Replacement bed thermistor
Thermal paste for thermistor mounting
Replacement Buddy/xBuddy board (if MOSFET failure)
Related Error Codes
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