Prusa error 13525 (Loadcell Tare Failed) appears on the MK4 and its equivalents are #26525 on the MK4S, #21525 on the MK3.9, and #31525 on the CORE One. The loadcell tare sequence — which establishes the zero-force baseline the sensor uses to detect nozzle contact — could not complete because the sensor readings were too unstable to lock a reliable zero point.

What the Error Means

Taring a loadcell means zeroing it while no force is applied, so the sensor can accurately measure small changes from that zero point. For the MK4 Nextruder loadcell, this happens before every first-layer probe cycle. If the tare fails, it usually means something is imposing a variable load on the sensor during the measurement window — either external vibration from the surface the printer is on, a loose or incorrectly torqued nozzle that allows the hot end assembly to shift slightly, or a loadcell cable that is under tension and pulling on the sensor mount. A damaged loadcell is a less common but possible cause.

Step-by-Step Fix

1. Place the printer on a stable, vibration-free surface. Even minor vibration from a washing machine running in the same room or a wobbly table can destabilize loadcell readings during taring. Move the printer to a solid, level surface.
2. Verify the nozzle is tightened to the correct torque. The nozzle should be tightened with the hotend at 270°C (never cold-tighten). A loose nozzle allows micromovements during taring that register as force fluctuations.
3. Run Calibrations & tests → Loadcell test to retry tare. From the menu, initiate the loadcell test — it includes a tare step and gives direct feedback on sensor stability.
4. Inspect the loadcell cable connector. With the printer off, check the loadcell cable at both the Nextruder-side connector and at the xBuddy board. A cable with excessive tension routed too tightly can pull on the sensor and cause reading drift.
5. Replace the loadcell sensor if tare repeatedly fails. If the printer is on a stable surface, the nozzle is properly torqued, and the cable is correctly routed, a failed loadcell sensor may be the root cause.

Parts Required

• Replacement loadcell sensor (if sensor readings remain unstable after all checks)
• Digital torque screwdriver or wrench (to correctly tighten the nozzle at temperature)

If the tare continues to fail after placing the printer on a stable surface and verifying nozzle torque, contact Prusa Support at help.prusa3d.com for assistance with loadcell replacement.

Frequently asked questions

What does Prusa 13525 mean?

Prusa error 13525 (Loadcell Tare Failed) appears on the MK4 and its equivalents are #26525 on the MK4S, #21525 on the MK3.9, and #31525 on the CORE One. The loadcell tare sequence — which establishes the zero-force baseline the sensor uses to detect nozzle contact — could not complete because the sensor readings were too unstable to lock a reliable zero point.

How do I fix Prusa 13525?

Prusa error 13525 means the loadcell could not establish a stable zero reading. Learn how to check nozzle torque, eliminate vibration, and inspect loadcell wiring.