Prusa error 13528 (Loadcell Timeout) appears on the MK4 and its equivalents are #26528 on the MK4S, #21528 on the MK3.9, and #31528 on the CORE One. The firmware attempted to read data from the loadcell sensor but the sensor did not respond within the expected time window, preventing the bed probing or tare operation from completing.

What the Error Means

The Nextruder loadcell communicates with the Buddy board over a dedicated interface. A timeout means the sensor either stopped transmitting entirely or its responses arrived outside the firmware’s acceptable window. Loose or damaged connector pins at either end of the loadcell cable are the most likely hardware cause. A mechanical overload on the Nextruder — such as debris jamming the extruder gears or an obstruction preventing the nozzle from moving freely — can also stress the loadcell beyond its operating range and trigger a communication fault. In rarer cases, this is a transient firmware glitch resolved by a restart.

Step-by-Step Fix

1. Restart the printer and retry the operation. If the timeout was transient, a fresh boot will clear it. Attempt the print or calibration again after restarting.
2. Inspect the loadcell cable and connectors. With the printer off, trace the loadcell cable from the Nextruder body to its connector on the xBuddy board. Unplug and firmly reseat both connectors. Check for kinks, cuts, or bent connector pins.
3. Check for debris in the Nextruder mechanism. Filament fragments or other debris inside the Nextruder can mechanically jam the extruder drive, placing excess force on the loadcell. Remove and reload filament, then inspect the extruder entry for obstructions.
4. Run the Loadcell test from Calibrations & tests. This standalone test provides direct sensor feedback and will tell you whether the loadcell is communicating at all, or whether the timeout is consistently reproducible.
5. Contact Prusa Support if the timeout recurs across multiple attempts. If the loadcell never completes a reading, describe the error frequency and the results of the loadcell test when you contact support.

Parts Required

• No replacement parts are typically required for this fix — basic tools only
• Replacement loadcell cable or sensor (if cable is confirmed damaged or sensor does not respond)

If the loadcell test confirms a non-responding sensor, contact Prusa Support at help.prusa3d.com for guidance on loadcell replacement.

Frequently asked questions

What does Prusa 13528 mean?

Prusa error 13528 (Loadcell Timeout) appears on the MK4 and its equivalents are #26528 on the MK4S, #21528 on the MK3.9, and #31528 on the CORE One. The firmware attempted to read data from the loadcell sensor but the sensor did not respond within the expected time window, preventing the bed probing or tare operation from completing.

How do I fix Prusa 13528?

Prusa error 13528 means the loadcell sensor stopped responding within its expected time window. Learn how to check the cable, connectors, and Nextruder for issues.