Description

Prusa Hall Filament Sensor — OEM Replacement

This is the OEM Hall effect filament sensor for the Prusa Nextruder — the sensor that detects whether filament is present and moving through the extruder. It’s what allows your printer to pause automatically if filament runs out or fails to feed, rather than continuing to print in thin air and ruining the job.

If your printer isn’t detecting filament runout, is throwing false “no filament” errors with filament clearly loaded, or the filament sensor has physically failed, this is the direct replacement.

What the Hall Filament Sensor Does

Unlike simple mechanical filament sensors that only detect presence, a Hall effect sensor detects the movement of filament through the extruder using magnetic field changes. This means it can distinguish between filament that is present but not moving (a jam or feeding failure) and filament that has genuinely run out — giving more reliable runout and jam detection than basic switch-based sensors.

When to Replace

Printer fails to detect filament runout and continues printing with no filament, false “insert filament” or “no filament” errors while filament is clearly loaded and feeding correctly, inconsistent or intermittent sensor readings during printing, and as part of Nextruder extruder maintenance or troubleshooting when filament detection issues persist.

Before replacing, check that the filament path is clean and the sensor area isn’t blocked by debris or filament dust — this is a common cause of false readings that doesn’t require a replacement part.

What’s Included

Hall filament sensor × 1

Compatibility

Prusa MK3.9 / MK3.9S
Prusa MK4 / MK4S
Prusa XL
Prusa CORE One / CORE One+
Prusa CORE One L

Not compatible with the MK3/MK3S/MK3S+, Prusa MINI/MINI+, or any non-Nextruder printer.

Installation

Refer to the Prusa Knowledge Base repair manual for your specific printer model at help.prusa3d.com. The sensor connects via the LoveBoard on CORE One and MK4/MK3.9 printers. Power off and cool the printer before starting the replacement.