Prusa error 13833 (Probing Failed) appears on the MK4 and its equivalents are #31833 on the CORE One, #35833 on the CORE One L, #17833 on the XL, #26833 on the MK4S, #27833 on the MK3.9S, #21833 on the MK3.9, #28833 on the MK3.5S, #23833 on the MK3.5, and #12833 on the MINI. Mesh bed leveling failed because the probe — the loadcell on MK4-family printers — could not reliably detect the bed surface at one or more probe points.

What the Error Means

MK4-family printers probe the bed before every print by pressing the nozzle lightly against the PEI sheet surface and using the loadcell to detect the contact force. If the loadcell cannot detect a consistent contact event — because filament residue on the nozzle tip is absorbing the contact force, because the steel sheet is not seated flat and an edge is lifting, or because the loadcell sensor or its wiring has developed a fault — the probing routine fails. On non-loadcell models, a probe sensor malfunction or incorrect assembly produces the same error through an analogous detection failure.

Step-by-Step Fix

1. Clean the nozzle tip thoroughly. This is the most common fix. Heat the nozzle to printing temperature, then wipe the tip with a brass brush or heat-resistant cloth until the metal surface is clean and bare. Cooled filament residue on the tip creates a soft buffer between the nozzle and bed surface that the loadcell cannot reliably detect.
2. Ensure the steel sheet is flat and properly seated. Remove the PEI sheet, wipe the magnetic bed surface clean, and re-seat the sheet so all four corners are flat against the bed. A lifted corner causes the probe to detect contact at a different height than expected.
3. Verify the nozzle is tightened to specification. Tighten the nozzle at 270°C — a loose nozzle allows micromovements that confuse the loadcell. Do not cold-tighten.
4. Run Calibrations & tests → Loadcell test. From the menu, run the standalone loadcell test to verify the sensor responds correctly to applied force. This isolates whether the issue is sensor-specific or surface/nozzle-related.
5. Inspect the loadcell wiring. With the printer off, check the loadcell cable connections at the Nextruder and at the xBuddy board. A loose or damaged cable causes intermittent sensor failures.
6. Contact Prusa Support if the loadcell test fails. A loadcell that produces inconsistent or zero-force readings has failed and requires replacement.

Parts Required

• No replacement parts are typically required for this fix — basic tools only
• Replacement loadcell (if the loadcell test confirms a sensor fault — contact Prusa Support)

If probing fails consistently even with a clean nozzle and flat steel sheet, contact Prusa Support at help.prusa3d.com with the results of the loadcell test.

Frequently asked questions

What does Prusa 13833 mean?

Prusa error 13833 (Probing Failed) appears on the MK4 and its equivalents are #31833 on the CORE One, #35833 on the CORE One L, #17833 on the XL, #26833 on the MK4S, #27833 on the MK3.9S, #21833 on the MK3.9, #28833 on the MK3.5S, #23833 on the MK3.5, and #12833 on the MINI. Mesh bed leveling failed because the probe — the loadcell on MK4-family printers — could not reliably detect the bed surface at one or more probe points.

How do I fix Prusa 13833?

Prusa error 13833 means mesh bed leveling probing failed. Learn how to clean the nozzle, verify the loadcell, and check the steel sheet to restore reliable first-layer probing.