Prusa error 13114 (Filament Sensor Troubleshooting) appears on the MK4 and is reported as #26114 on the MK4S, #21114 on the MK3.9, #27114 on the MK3.9S, #23114 on the MK3.5, #28114 on the MK3.5S, and #31114 on the CORE One. The filament sensor located on the printhead detected a blockage near its position — typically accumulated debris has made the sensor unresponsive or unreliable.

What the Error Means

The filament sensor on MK4-family printers uses an optical or magnetic mechanism inside the extruder assembly to detect whether filament is present and moving. Over time, filament dust, polymer debris, and grease can accumulate inside the sensor cavity, causing the sensor to give false readings or fail to detect filament at all. The error indicates debris has built up to the point where the sensor cannot function correctly. This is a maintenance issue rather than a hardware failure and is typically resolved by cleaning.

Step-by-Step Fix

1. Use compressed air as the first approach. Locate the small hole at the top of the extruder housing (above the filament entry point). Insert the tip of a compressed air canister into the hole. Repeatedly insert and remove a short piece of filament while blowing air — the filament agitates debris loose while the air purges it out.
2. Loosen the chimney cover (MK3.5/S). On MK3.5 and MK3.5S models, use a 1.5 mm Allen key to loosen the one M2×8 screw on the chimney assembly cover. Remove the cover carefully and use a small brush or compressed air to remove debris from the exposed sensor area. Reinstall the cover and tighten the screw.
3. Remove the ball-magnet-spring for a thorough clean. For a full clean on any supported model, use needle-nose pliers to remove the Prusa-ball-holder component. Pull out the ball-magnet-spring assembly as a unit. Clean debris from the slot on the heatsink that houses the assembly. Reassemble in reverse order, ensuring the spring seats correctly.
4. Recalibrate the filament sensor after cleaning. After reassembly, recalibrate the sensor through the printer menu: navigate to LCD Menu → Settings → Filament Sensor and follow the calibration prompts. Calibration ensures the sensor correctly detects the presence and absence of filament after the cleaning disturbs its reference state.

Parts Required

• No replacement parts are typically required for this fix — basic tools only
• Compressed air canister
• 1.5 mm Allen key (MK3.5/S chimney cover screw)
• Needle-nose pliers (to remove ball-holder)
• Replacement filament sensor assembly (only if sensor is physically damaged after inspection)

If the sensor continues to report errors after a full clean and recalibration, contact Prusa Support — the sensor component may need replacement.

Frequently asked questions

What does Prusa 13114 mean?

Prusa error 13114 (Filament Sensor Troubleshooting) appears on the MK4 and is reported as #26114 on the MK4S, #21114 on the MK3.9, #27114 on the MK3.9S, #23114 on the MK3.5, #28114 on the MK3.5S, and #31114 on the CORE One. The filament sensor located on the printhead detected a blockage near its position — typically accumulated debris has made the sensor unresponsive or unreliable.

How do I fix Prusa 13114?

Prusa error 13114 means the filament sensor on the printhead is blocked by debris. Clean the sensor with compressed air or disassemble for a full clear.