Prusa error 13113 (Filament Sensor Stuck) appears on the MK4 and its equivalents are #31113 on the CORE One, #35113 on the CORE One L, #17113 on the XL, #26113 on the MK4S, #27113 on the MK3.9S, #21113 on the MK3.9, #28113 on the MK3.5S, #23113 on the MK3.5, and #12113 on the MINI. The filament sensor is reporting that filament is present continuously — even when filament has been removed — indicating the sensor lever or detection mechanism is jammed in the triggered state.

What the Error Means

The filament runout sensor uses a mechanical lever or optical gate to detect whether filament is present in the extruder path. When a small fragment of filament gets wedged against the sensor lever, the sensor is held in the “filament present” position even after the main filament strand is removed. This prevents the sensor from detecting a real runout event during printing, defeating the purpose of the runout protection. The error is also triggered when the sensor itself has failed in a way that produces a constant “present” signal.

Step-by-Step Fix

1. Remove the filament and inspect the sensor area. Unload the filament from the printer and visually inspect the extruder entry and sensor area with a flashlight. Look for a small filament tip or fragment pressing against the sensor lever.
2. Insert and remove filament repeatedly. Loading and unloading filament a few times can dislodge a small piece of filament that is barely catching the sensor lever. Watch whether the sensor reading changes as you do this.
3. Use compressed air to clear the sensor area. Insert a compressed air nozzle into the top extruder entry port and give a short burst to dislodge any debris that cannot be reached manually.
4. Use a thin implement to clear stubborn jams. A straightened paper clip or a thin piece of wire (power off first) can be carefully used to push visible fragments away from the sensor lever. Avoid using sharp tools that could scratch the sensor.
5. Disable the filament sensor as a temporary workaround. Navigate to LCD Menu → Settings → Filament Sensor and disable it. This allows printing to continue but removes runout protection — re-enable the sensor once you resolve the underlying cause.
6. Contact Prusa Support if debris is cleared but the error persists. A sensor that reads “stuck” after the channel is physically clear has likely failed electrically.

Parts Required

• No replacement parts are typically required for this fix — basic tools only
• Replacement filament sensor (if the sensor has failed electrically — contact Prusa Support)
• Compressed air canister

If the sensor continues to read as stuck after the extruder channel is clear, contact Prusa Support at help.prusa3d.com.

Frequently asked questions

What does Prusa 13113 mean?

Prusa error 13113 (Filament Sensor Stuck) appears on the MK4 and its equivalents are #31113 on the CORE One, #35113 on the CORE One L, #17113 on the XL, #26113 on the MK4S, #27113 on the MK3.9S, #21113 on the MK3.9, #28113 on the MK3.5S, #23113 on the MK3.5, and #12113 on the MINI. The filament sensor is reporting that filament is present continuously — even when filament has been removed — indicating the sensor lever or detection mechanism is jammed in the triggered state.

How do I fix Prusa 13113?

Prusa error 13113 means the filament sensor is permanently triggered. Learn how to clear debris from the sensor, reload filament, and restore accurate runout detection.