AMS Filament Detection Issues
Follow the steps in order, starting with the hall sensors.
Clean the hall sensors
Power off the printer. Remove all filament from the AMS. Blow compressed air into each slot, then clean the sensor area at the back of each slot with a dry cotton swab.
Reload filament and test. Never use force, stop immediately if you hear grinding or feel resistance.
Check RFID & set material manually
RFID tags only work with Bambu-brand spools. For third-party filament, simply set the material type manually in Bambu Studio: the printer works just as well without RFID.
| "RFID not recognized" | Third-party spool or damaged tag |
| "Filament may be broken" | Filament snapped inside the AMS (PTFE tube or hub): push the piece out with a fresh length of filament or clear the hub, see AMS jamming |
| "Failed to feed filament" | Feeder slip or tangled spool |
| "Please load filament" | Filament not reaching the sensor |
Clean the feeder gears
Remove all filament and inspect the feeder gears through the slot opening for debris. Clean the gear teeth with a soft brush or compressed air.
Also check that the spool unwinds freely, too much tension from a tangle can stall the feeder motor.
Inspect the filament buffer
On X1, P1 and P2S printers the filament buffer sits on the back of the printer, between AMS and toolhead. Inside are a slider, a spring and a Hall sensor that reads the slider position. Power off, remove the buffer (X1/P1: two screws, H2.0 hex key), unplug the 4-pin and 6-pin cables and both PTFE tubes, then push a short piece of filament through; it should pass freely. On the P2S follow Bambu's buffer cleaning guide (H1.5 hex key, remove the top cover and circuit board, clear debris around the Y-shaped path). If it still sticks after cleaning, replace the buffer.
X2D: the buffer also sits on the back, held by two screws (H2.0 key); see Bambu's X2D buffer guide. H2D, H2C and H2S: the buffer is built into the printer (on the H2S in the top cover, with two sliders and two springs); follow Bambu's H2S buffer guide. With a full AMS on an A1 series printer, the A1 Series AMS Hub takes the buffer's place (Bambu's AMS connection guide).
A stuck buffer falsely reports no filament movement and interrupts the print unnecessarily.
Less common causes
If steps 1–4 didn't help, expand the topic that matches your situation:
Kinked PTFE tubes inside the AMS hub cause intermittent detection errors. Pull out each tube and manually thread a short piece of filament through, there should be no noticeable resistance. Replace any kinked sections; they are cheap and easy to swap.
Check the AMS firmware version, some detection errors were bugs fixed in updates. AMS Lite (A1 series) has a simplified detection system; most steps still apply, but the hub and buffer design differ.
Load filament directly into the extruder (bypassing the AMS) to check whether the issue is on the AMS side. If the print works without the AMS, the AMS system is faulty. Contact Bambu Lab Support in that case, hall sensor failures sometimes require replacement parts.
Still not working? Interactive troubleshooter · Community
Tools that fix this
Keep the feed path clean so the AMS reads filament reliably.
Capricorn XS, 1.9 mm ID, for replacing kinked or worn tubes. Narrower than Bambu's stock tubes (2.0 mm inside the AMS and on the X1/P1, 2.5 mm on the A1, A1 mini, A2L, P2S, X2D, H2C, H2D and H2S); Bambu advises against a smaller ID because it adds friction. In our own printers it has still worked better than the stock tube, which is why we keep recommending it; if feeding gets worse, go back to the stock size.
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Swollen or shedding wet filament fouls the AMS odometer and hub; drying it prevents false runout and feed errors.
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Nothing worked?
Ask in the official Bambu Lab forum or open a ticket via Bambu Lab support; photos help a lot. You can also contact us or post in our community forum. Or try the interactive troubleshooter.