The AMS won't load filament: «Failed to feed», assist motor overloaded or no extrusion

Symptom

With an AMS (also AMS 2 Pro or AMS HT) loading or a colour change stops with an alert: the filament does not leave the AMS (0700-8005, «Failed to feed the filament outside the AMS»), does not reach the toolhead (0700-8006), the assist motor is overloaded (0700-8010) or the toolhead cannot extrude it (0700-8007). With more AMS units, the codes start with 0701, 0702 and so on.

Likely causes, from most to least likely

1. Stuck spool or tangled filament, or a spool that does not fit: the AMS takes spools 50 to 68 mm wide and 197 to 202 mm in diameter, and cardboard spools can slip and leave debris unless fitted with an adapter ring.
2. Broken filament in the path (inside the AMS, in a PTFE tube or near the toolhead) blocking the next one, especially with brittle or damp filament.
3. Worn PTFE tubes or damaged couplers: the filament always stops at the same point.
4. The filament slips on the AMS internal drive wheel (you can see marks on it) or the first-stage feeder of that slot is failing.
5. The toolhead extruder is blocked or cannot grip the filament: the AMS delivers it but extrusion fails.
6. Material not suited to the AMS: TPU, TPE or PVA, or third-party fibre-filled filaments that are too hard or too brittle.

Checks to tell which one it is

• See how far the filament gets: if it never comes out of the rear AMS tube, the fault is inside the AMS; if it comes out but does not reach the toolhead, look at the tubes or the toolhead.
• Push a filament by hand up to the toolhead and see whether the green extruder dot lights up in Bambu Studio (device tab) or, on the X series, on the temperature and axis screen: it means the toolhead sensor detects it.
• Take the spool out, check that it turns freely and that the filament is not crossed, and look for bite marks on the filament.
• Try another spool and notice whether the fault always happens in the same slot.

Before you start

Before taking anything apart, cleaning or adjusting it, switch the printer off and unplug it, unless a step says otherwise, and do not touch the nozzle, the heater block or the bed until they have cooled down. If in any doubt about electricity, heat or moving parts, stop and ask a professional.

Step-by-step fix

1. Untangle, check the spool and trim the tip

   Open the AMS, check that the spool turns without rubbing and untangle the filament. Cut the tip flat, insert it again and press «Retry». Fit cardboard spools with an adapter ring, and do not put TPU, TPE or PVA in the AMS.

   Check: Loading finishes and the filament reaches the toolhead.

   If that does not fix it: Look for broken filament in the path (next step).

2. Remove broken filament from the path

   Switch the printer off. Release the PTFE tube at the AMS outlet by pressing its lock and pull out the broken piece. If it is between the AMS and the printer or near the toolhead, release the tube at that point and push it out with another piece of filament. If it snapped inside the toolhead, clean the extruder following the guide for your model.

   Check: The tubes are clear and a filament passes end to end without catching.

   If that does not fix it: Check the tubes and couplers (next step).

3. Check PTFE tubes and couplers

   If the filament always stops at the same place, remove the tube at that coupler and check it for damage, or swap the tube ends. Bambu Lab treats PTFE tubes as consumables: 2.5 mm inner and 4 mm outer diameter, to be replaced every 2 months in normal use or every month with abrasive filaments.

   Check: The filament no longer stops at that point.

   If that does not fix it: Replace the damaged coupler or tube and check the drive wheel (next step).

4. If the filament slips inside the AMS

   If you see marks or bites on the filament, try another spool and, with the printer off, tighten the 4 screws of the internal drive assembly shown in the Bambu Lab guide. If it still slips, the active drive wheel may need replacing.

   Check: The filament moves without new marks.

   If that does not fix it: Record a video and contact Bambu Lab support with the printer logs.

5. If the LED does not react or the feeder does not pull

   If the slot LED does not change when you insert about 10 cm of filament, or it changes but the motor does not pull the filament in, switch the printer off and clean that slot's feeder inlet: push out debris or broken pieces with a short length of filament and clean the knurled wheel and gear following the Bambu Lab guide.

   Check: When you insert filament, the LED changes and the AMS pulls it in.

   If that does not fix it: If the motor still does not turn after reconnecting its cable, that slot's feeder unit needs replacing.

6. If the AMS delivers the filament but it does not extrude

   If the green extruder dot lights up but the extrusion error appears, load a filament by hand from the external spool holder: if that does not extrude either, the extruder or nozzle is clogged and must be cleaned; if the external spool works, check the filament buffer using its guide.

   Check: The filament comes out of the nozzle when loading from the AMS.

   If that does not fix it: Upload the logs and contact Bambu Lab support: the AMS internal hub motor may be at fault.

Prevention

• Use spools within the AMS size limits and fit cardboard spools with an adapter ring.
• Keep filament dry: damp or brittle filament snaps inside the tubes and the toolhead.
• Check the PTFE tubes for wear at every maintenance; the printer reminds you to check them every 2 months.
• Print TPU, PVA and hard fibre-filled filaments from the external spool holder.

Still not fixed?

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Printers it applies to

Bambu Lab's FDM printers: A1, A1 mini, A2L, H2C, H2D, H2D Pro, H2S, P1P, P1S, P2S, X1, X1 Carbon, X1E and X2D.

Official sources

This guide summarises the official documentation linked here:

• AMS filament loading & unloading failure troubleshooting (pull back/unload issues) · Bambu Lab
• Notes for AMS · Bambu Lab
• Filament break in the path · Bambu Lab
• PTFE Tube Wear in AMS and Maintenance Recommendations · Bambu Lab
• Abnormal AMS LED Status Troubleshooting · Bambu Lab
• Error Code · Bambu Lab