Prusa error codes: what they mean on the MK4S, CORE One and MINI+
Prusa printers show a five digit error code with a QR code that links to a help article. The first two digits name the printer, the third is the category, and the last two are the error. This page covers the most common codes on the CORE One, MK4S and MINI+ and the fix Prusa gives.
Researched by Riley Hart · updated Oct 27, 2026 · How we research
As of October 27, 2026, Prusa error codes follow the pattern XXYZZ. XX is the printer (12 is the MINI, 13 the MK4, 26 the MK4S, 31 the CORE One), Y is the category (1 mechanical, 2 temperature, 3 electrical, 4 connectivity, 5 system, 6 bootloader, 7 and 8 warnings), and ZZ is the error. The most common are heating and thermistor errors such as XX202 preheat error and XX204 thermal runaway on the print head, stuck filament (XX101), steel sheet not detected (XX109) and failed homing (XX301, XX304, XX305). Scan the QR code on the screen or enter the code at help.prusa3d.com for the exact fix.
| Code | What it means | What to do |
|---|---|---|
| XX101 | Stuck filament detected (MK4/S, CORE One) | Unload the filament from the Nextruder and load it again |
| XX109 | Steel sheet not detected (MK4/S, CORE One) | Put the steel sheet on the bed before continuing |
| XX110 | Door open (CORE One) | Close the door to avoid drafts and burns |
| XX111 | Uneven bed (CORE One) | Run the Z alignment procedure |
| XX113 / XX114 | Filament sensor not responding | Clean debris from the filament sensor, or turn it off for now |
| XX116 | Several filament loading errors recorded | Run Nextruder maintenance and clean the main plate inside it |
| XX201 | Bed preheat error | Check the heatbed heater and thermistor wiring for damage |
| XX202 | Print head preheat error | Check the print head heater and thermistor wiring for damage |
| XX203 | Bed thermal runaway | Check the heatbed thermistor wiring for damage |
| XX204 | Print head thermal runaway | Check the print head thermistor wiring for damage |
| XX205 / XX206 | MAXTEMP error on the bed or print head | Check that thermistor's wiring for damage |
| XX207 / XX208 | MINTEMP error on the bed or print head | Check that thermistor's wiring for damage |
| XX209 / XX210 | Measured temperature does not match the expected value | Make sure the thermistor touches the bed or hotend; replace it if damaged |
| XX211 / XX212 | Heatbreak MINTEMP or MAXTEMP error | Check the heatbreak thermistor wiring |
| XX260 / XX261 | Chamber overheating or critical (CORE One) | Improve ventilation; the print is stopped at the critical level |
| XX301 | Z homing failed | MK4/S and CORE One: check the loadcell. MINI: the SuperPINDA may be broken or unplugged |
| XX304 / XX305 | X or Y homing failed | Remove anything blocking that axis |
| XX308 | Nozzle heater overcurrent | Power off, check the heater cable for damage, contact Prusa support if it repeats |
| XX321 | Power panic detected at startup | Check the power panic cable |
| XX323 | Accelerometer communication failed | Check that the accelerometer cable is plugged in and not damaged |
| XX523 to XX528 | Loadcell not calibrated, tare failed or timed out | Restart and calibrate the loadcell; check its wiring |
| XX534 | G-code on the USB drive is corrupt | Slice and copy the file again |
| XX613 / XX703 | USB drive file system error | Use another drive or format it as FAT32 |
| XX810 | Crash detected: axis too short | Look for an obstacle or a bearing problem |
| XX816 | Print fan not spinning | Check the fan for debris, then the wiring |
| XX828 | Hotend fan not spinning | Check the fan for debris, then the wiring |
| XX833 | Bed leveling failed | Clean the nozzle and sheet, then try again |
| XX834 | Nozzle cleaning failed | Clean the nozzle by hand and retry |
| XX836 | Filament loading timed out | Check the filament path and load again |
From Prusa's official error code list on GitHub (Prusa-Error-Codes, buddy firmware) and the Prusa Knowledge Base, checked October 27, 2026. Replace XX with your printer number, for example 26204 on an MK4S or 31203 on a CORE One. Not every code applies to every model. The full list has about 260 entries for the buddy firmware printers.
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How to read a Prusa error code
Current Prusa printers show a red error screen or a warning dialog with a title, a short message and a QR code. Scan the code with your phone and it opens the help article for that exact error. You can also type the link shown on screen or search the code at help.prusa3d.com.
Every code has five digits. Prusa uses 12201 on the MINI as its example: 12 is the printer, 2 is the temperature category, and 01 means the heatbed heating failed. The printer number comes from its USB ID. The MINI and MINI+ use 12, the MK4 uses 13, the MK4S uses 26 and the CORE One uses 31. So a bed thermal runaway shows as 26203 on an MK4S and 31203 on a CORE One.
The middle digit tells you where to look. 1 is mechanical, 2 is temperature, 3 is electrical, 4 is connectivity, 5 is system, 6 is the bootloader used for firmware updates, and 7 and 8 are warnings and prompts.
Heating and thermistor errors
Temperature codes in the 2xx range are the ones that stop prints most often. A preheat error (XX201 or XX202) means the bed or hotend did not heat as expected. A thermal runaway (XX203 or XX204) means the temperature dropped or failed to hold while the heater was on. MAXTEMP and MINTEMP errors mean a reading was outside the possible range, which often points to a broken or shorted thermistor wire.
For each one, Prusa says to check the heater and thermistor wiring for damage. Turn the printer off, let it cool, and look for crushed, pinched or loose cables at the print head and bed. A draft can also cause thermal runaway on an open frame printer, so keep it away from fans and open windows. If the reading does not match the real temperature (XX209 or XX210), check that the thermistor is seated in the heater block or bed.
Homing, loadcell and sheet errors
The MK4S and CORE One use a loadcell in the Nextruder to sense the bed. If Z homing fails (XX301), Prusa says to make sure the loadcell is working. Loadcell errors XX523 to XX528 usually clear after a restart and a fresh calibration. If they return, check the loadcell cable.
On the MINI+, the same Z homing code points to the SuperPINDA sensor, which may be broken or unplugged. X and Y homing errors (XX304 and XX305) mean the axis hit something early, so check for debris, a loose part or a cable caught in the path. Steel sheet not detected (XX109) simply means the sheet is missing or not seated.
Filament and fan errors
XX101 means the filament seems stuck. Unload it from the Nextruder and load it again. If it keeps happening, XX116 may appear, which tells you the printer has logged several loading errors and asks you to service the Nextruder. A cold pull, offered on the printer as XX702, is Prusa's way to clean a partly clogged nozzle with a 30 cm piece of PLA.
Fan warnings XX816 and XX828 mean the print fan or hotend fan is not spinning. Prusa says to check the fan for debris first, then the wiring. A hotend fan that stops can lead to heat creep and clogs, so do not ignore it.
When a repeat error means a worn part
Some Prusa codes are maintenance reminders. XX117 tells you filament changes have reached the expected life of the Nextruder main plate and suggests having a spare ready. On the CORE One, XX831 and XX832 warn that the HEPA filter is near or past the end of its life.
Other repeats point to wear. Stuck filament codes that come back with dry filament and a cold pull suggest a worn nozzle or a damaged PTFE tube in the heatbreak. Thermistor errors that return after you reseat the cables usually mean the thermistor or its wire is broken. A fan warning that repeats with a clean fan means the fan is failing. Prusa notes that some errors need a part replaced, and its help articles link the matching service guide.
When to contact Prusa support
Contact Prusa if an electrical code such as XX308 nozzle heater overcurrent appears, if XX538 internal error appears (Prusa asks for the crash dump saved on reset), or if XX601 unknown error appears. Also reach out if a temperature or homing error keeps returning after the wiring checks.
Prusa offers chat and email support through its website. Have the full five digit code, your printer model and serial number, and the firmware version ready. Keep the printer on current firmware, because older versions can show different screens or codes. If the printer is still under warranty, ask support before replacing electronics yourself.
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Questions people ask
What does Prusa error 26204 mean?
26 is the MK4S, 2 is the temperature category and 04 is thermal runaway on the print head. Prusa says to check the print head thermistor wiring for damage.
How do I look up a Prusa error code?
Scan the QR code on the printer screen, open the link shown under it, or search the five digit code at help.prusa3d.com. Each code has its own article with the fix.
What does steel sheet not detected mean on a Prusa?
Code XX109 means the printer cannot sense the steel sheet. Put the sheet on the bed and make sure it sits flat and is locked in place before you continue.
Why does my Prusa say stuck filament detected?
Code XX101 means the filament seems stuck in the Nextruder. Unload it and load it again. If it repeats, try a cold pull and dry your filament.
What does the middle digit of a Prusa error code mean?
It is the category: 1 mechanical, 2 temperature, 3 electrical, 4 connectivity, 5 system, 6 bootloader, and 7 or 8 for warnings.