Prusa error 13201 (Bed Preheat Error) fires on the MK4, and its equivalents appear as #26201 on the MK4S, #21201 on the MK3.9, #27201 on the MK3.9S, #23201 on the MK3.5, #28201 on the MK3.5S, and #31201 on the CORE One. The printer detected that the heatbed temperature did not climb more than 2°C within the first 20 seconds of a preheat cycle.

What the Error Means

The firmware monitors bed temperature rise at the start of every preheat. If the bed gains less than 2°C in 20 seconds, it concludes that the heating circuit is not functioning and halts to prevent thermal runaway. The three most common causes are a damaged heatbed thermistor or power cable, a loose connector at the xBuddy board, and an ambient room temperature below 18°C — cold air slows initial temperature rise enough to trigger the threshold.

Step-by-Step Fix

1. Check ambient temperature. Make sure the room is warmer than 18°C. Cold environments slow the initial heat rise and can trigger this error even when hardware is healthy.
2. Inspect the thermistor seating. Power off the printer and let it cool completely. Lift the heatbed and confirm the thermistor is secured flat under the golden Kapton tape at the bed surface. A displaced thermistor reads ambient air instead of bed temperature.
3. Check the round cable connector. Verify the washer is positioned above — not below — the round heatbed cable connector. An improperly seated washer can create intermittent contact.
4. Confirm the M3nN nut. The M3nN nut should hold the connector screw firmly in place. Tighten if loose.
5. Inspect xBuddy board connections. Open the electronics enclosure and reseat the heatbed thermistor and heater cables at the xBuddy board. Look for bent pins, frayed insulation, or connectors that pull out too easily.
6. Test with a multimeter. Measure the thermistor resistance (expect roughly 100 kΩ at room temperature for an NTC 100k thermistor) and heater resistance to isolate which component has failed.

Parts Required

• Replacement NTC 100k thermistor (if thermistor resistance is out of range)
• Replacement heatbed power cable (if cable shows visible damage or high resistance)
• Kapton tape (to re-secure thermistor if adhesive has failed)
• Digital multimeter

If the error persists after completing all steps, contact Prusa Support at help.prusa3d.com with your multimeter readings for further assistance.

Frequently asked questions

What does Prusa 13201 mean?

Prusa error 13201 (Bed Preheat Error) fires on the MK4, and its equivalents appear as #26201 on the MK4S, #21201 on the MK3.9, #27201 on the MK3.9S, #23201 on the MK3.5, #28201 on the MK3.5S, and #31201 on the CORE One. The printer detected that the heatbed temperature did not climb more than 2°C within the first 20 seconds of a preheat cycle.

How do I fix Prusa 13201?

Prusa error 13201 means the heatbed failed to rise 2°C in 20 seconds. Learn how to diagnose and fix thermistor, cable, and board connection issues.