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P
12201
Easy Fix
Prusa · FDM 3D Printers
MINTEMP Hotend - Thermistor Reading Below Minimum Threshold
Quick Answer
Error code 12201 on your Prusa FDM 3D Printers means: MINTEMP Hotend - Thermistor Reading Below Minimum Threshold. This is usually fixable — see the step-by-step guide below.
Affected Models
Applies to all models
MINI+MK3.5MK3S+MK4MK4SXL
Likely Causes
  1. Hotend thermistor connector disconnected from the Buddy or xBuddy mainboard
  2. Thermistor wire broken internally, often near the heat block where thermal cycling causes fatigue
  3. Corrosion on the thermistor connector pins due to moisture exposure
  4. Thermistor failed open circuit after prolonged use
How to Fix It
1
Open the electronics enclosure and verify the thermistor connector is fully seated on the mainboard
2
Measure thermistor resistance at room temperature with a multimeter (expect ~100K ohms at 25C for the Prusa NTC thermistor)
3
Inspect the thermistor cable for damage, especially where it exits the hotend assembly
4
If the MK4/MK4S, check the Nextruder thermistor connector on the dwarf board
Pro Tip
This is a common issue that most users can resolve without specialized tools. Try the first step before moving on to more complex solutions.
Parts You May Need
Prusa hotend thermistor (part number varies by model)
Replacement cable harness for Nextruder (MK4/MK4S)
Related Error Codes
1220212203122111221212213
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