AMS 2 Pro - First-stage feeder motor stops after one rotation on all slots

Bambu Lab P Series Troubleshooting
1

I am experiencing a persistent loading issue with my AMS 2 Pro where it fails to pull filament from any of the four slots.

Issue Description:

  • When initiating a load command, the first-stage feeder motor grabs the filament, rotates approximately one full revolution, and immediately stops.

  • This exact behavior occurs identically across all 4 slots.

  • No error code or warning message is displayed in Bambu Studio or on the printer screen when it stops.

Troubleshooting Already Performed:

  • Inspected all four first-stage feeders and internal channels; no broken pieces of filament or debris are present.

  • Manually pushed filament through the entire path—from the slots, through the PTFE tubes, internal hub, and all the way to the toolhead extruder—and it moves completely freely with zero physical resistance or blockages.

  • Checked and re-seated the PTFE tubes and the 6-pin bus cable connecting the AMS to the printer.

Could you please advise on what might be causing this sensor or motor stall across all slots, and how to resolve it?

2

What brand of filament are you using?

3

I am wondering if this some RFID tag weirdness? If you put in tagged / untagged materials, does it make a difference?

Otherwise, I don’t know.