Bambu Lab Filament Sensor Base — A1 Series

Bambu Lab Filament Sensor Base — A1 Series

It is a small grey bracket, but nothing on the A1 tool head works properly without it. The Filament Sensor Base sits on top of the extruder unit and does two jobs at once: it is the fixed mounting point for the filament sensor (Hall board) on its side, and it is the base the A1 series filament hub seats into. If the base is cracked after a tool-head knock, the screw bosses are stripped, or the sensor no longer sits square and your printer has started throwing odd filament detection behaviour, replacing the base is usually the real repair — not another sensor.

This is the genuine Bambu Lab part (FAC055), the same component fitted at the factory, held locally so you are not waiting on an overseas spare-parts order to get a printer back into service.

---

Key features

Genuine OEM part FAC055 A1 & A1 mini Mounts the Hall board sensor Seats the filament hub Plastic + metal 15-minute repair

• Correct geometry, every time. The sensor only reads reliably when it is held square to the filament path — a printed or bodged bracket will not hold that tolerance.
• Factory part, factory fit. Same moulding and metal insert as the base that shipped with your A1 or A1 mini, so screw torque and hub alignment are unchanged.
• Keeps the AMS lite working. The filament hub bolted to this base is what routes filament between the AMS lite and the extruder on multi-colour prints.
• Sensible spare. Small, cheap to hold and a common casualty of tool-head crashes — worth keeping in the drawer if you run a classroom, makerspace or print farm.

---

Who it is for

A1 and A1 mini owners doing their own maintenance; schools and makerspaces keeping a bin of consumable spares so a printer is never down for a week; small businesses and print farms where an idle A1 costs real money. The job is beginner-friendly — two screws, no soldering, no firmware steps — but it does involve removing the filament hub and handling the sensor wiring, so take your time the first time.

What is in the box

• 1 × Bambu Lab Filament Sensor Base (FAC055), grey

No screws and no hex keys are supplied. Bambu Lab ships this part on its own, so keep the two screws you remove from the old base somewhere safe — losing them means you cannot refit the new one. You will need an H2.0 hex key for the base screws and an H1.5 hex key for the sensor screws; both are in the tool kit that came with your printer.

---

Fitting it

1. Power the printer off at the wall first. Working on the electronics with the machine live risks a short circuit.
2. Unload and cut the filament, then remove the filament hub assembly from the top of the extruder unit.
3. Use the H2.0 hex key to undo the two screws holding the sensor base and lift the base up and off.
4. Use the H1.5 hex key to release the two screws on the filament sensor and transfer the sensor across to the new base.
5. Reverse the steps, refit the hub, power up and run a short test print to confirm filament detection is behaving.

Bambu Lab publishes the full illustrated procedure on its wiki under A1 / A1 mini → Maintenance → Filament sensor base replacement. Allow about 15 minutes.

---

Specifications

Product	Filament Sensor Base — A1 Series
Brand	Bambu Lab
OEM part number	FAC055
Compatibility	Bambu Lab A1 and A1 mini (A1 Series exclusive)
Not compatible with	P1P / P1S / P2S / X1 / X1C / X1E / X2D / H2 series
Function	Fixed mount for the filament sensor (Hall board) and base for the filament hub, fitted to the top of the extruder unit
Material	Plastic and metal
Colour	Grey
Package contents	Filament Sensor Base × 1 (screws not included)
Tools required	H2.0 and H1.5 hex keys (supplied with the printer, not with this part)
Package size	60 × 60 × 30 mm
Gross weight	0.01 kg (10 g)
Part type	Non-powered mechanical spare — no cables, plug pack or firmware update needed

---