Bambu Lab Extruder Filament Sensor — H2S

Bambu Lab Extruder Filament Sensor — H2S

Tucked inside the H2S extruder, the Extruder Filament Sensor is the small Hall-effect board that keeps your printer honest about what's loaded. It detects both the presence of filament and the position of the filament cutter lever — which is why a failing sensor can show up in two very different ways: phantom runouts and pauses mid-print, or cutter-related errors during a filament change.

This is the genuine Bambu Lab service part (FAC142) for the H2S and H2S Laser, supplied with the two mounting screws so you're not hunting through a parts bin. If you've chased a filament-detection fault through connector reseats and firmware updates and it still won't clear, this is the component to replace.

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Key features

Genuine Bambu Lab FAC142 Hall-effect sensing Filament presence detection Cutter lever position H2S & H2S Laser Mounting screws included ~20 minute fit

• Two jobs, one board. Bambu's own description is clear: the sensor sits in the extruder and detects the presence of filament as well as the position of the filament cutter lever. Both signals matter for reliable loading, unloading and automatic error reporting.
• A real diagnosis, not a shotgun fix. If your H2S reports the filament cutter sensor as malfunctioning, or keeps insisting filament is absent when it clearly isn't, the sensor and its connector are the first suspects.
• Service part, not an upgrade. This is a like-for-like replacement for the board already in your machine — no firmware changes, no recalibration beyond the normal load check afterwards.
• Sensible spare for busy machines. Schools, makerspaces and small production shops running H2S units back-to-back tend to keep one on the shelf so a sensor fault costs an hour, not a week.

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What's in the box

• 1 × Hall Effect Board Assembly (Extruder Filament Sensor, FAC142)
• 2 × BT2.6-6 screws

Not included: Allen keys, FPC cable, extruder unit or hotend. The H2.0 and H1.5 Allen keys needed for the job are standard printer tools, and the extruder hall sensor board is a separate part — don't confuse the two when ordering.

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Fitting it — the short version

Bambu Lab's official wiki rates this as a roughly 20-minute job. Summary only — follow the wiki guide for your machine as you work:

1. Power the printer off first. Working on tool-head wiring with the machine live risks a short circuit, electronic damage and injury.
2. Press the pneumatic connector to release the PTFE tube.
3. Remove the two mounting screws with an H2.0 Allen key. Don't pull hard on the sensor, and set it down carefully — the black FPC cable damages easily.
4. Use an H1.5 Allen key to undo the sensor cable's fixing screw, open the clip and unplug the connector.
5. Fit the new sensor by reversing the steps, then run a load/unload cycle to confirm detection is behaving.

Guide: wiki.bambulab.com — Replace Extruder Filament Sensor (H2S)

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Compatibility

Fits the Bambu Lab H2S and H2S Laser only. Other printers in the range use different sensors — the H2D and H2C take the Dual Extruder Idlers and Filament Sensor assembly, the X2D uses separate left and right sensors, and the P1, P2S and X1 series each have their own version. Check your model before ordering, or ask us and we'll confirm.

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Specifications

Product	Extruder Filament Sensor — H2S
Brand	Bambu Lab (genuine part)
OEM part number	FAC142
EAN / GTIN	6937285507242
Sensor type	Hall Effect Board Assembly
Detects	Filament presence + filament cutter lever position
Compatibility	H2S, H2S Laser
Materials	Plastic, metal
Colour	Black
In the box	Hall Effect Board Assembly × 1, BT2.6-6 screw × 2
Tools required	H2.0 and H1.5 Allen keys (not supplied)
Typical fitting time	Approx. 20 minutes
Package size	60 × 60 × 30 mm
Gross weight	0.02 kg

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