P1S + AMS: filament reaches the extruder sensor, but the extruder won’t grab it during AMS loading
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Hi everyone,
I’m having a strange issue with my Bambu Lab P1S + AMS.
When loading filament from the AMS, the filament travels all the way through the PTFE and appears to go past the filament sensor and into the extruder. In the video, you can see the filament reach that point, but the extruder drive gear spins without actually grabbing/feeding the filament. After a few seconds, the AMS retracts the filament.
The important part is:
In manual extrusion mode, the exact same filament is grabbed by the extruder normally and extrudes through the nozzle without any problem.
So the extruder is mechanically capable of feeding the filament.
Things I’ve already checked:
Original Bambu hotend installed/replaced.
Extruder disassembled and checked — no debris or broken filament inside.
PTFE tube trimmed and checked — filament moves smoothly through it.
Extruder mechanism is correctly assembled.
Manual extrusion works normally.
Tried all 4 AMS slots — exactly the same behavior.
Same filament works perfectly when manually inserted.
Downgraded the P1S firmware — no change :(
The video shows the filament apparently getting past the filament sensor, while the extruder gear spins but doesn't grab it.
Could this be a problem with the filament sensor / sensor logic during AMS loading, or is there another part of the toolhead that controls when the extruder engages during an AMS load?
I'm running:
P1S firmware: 01.10.00.00 (before downgrade)
AMS firmware: 01.00.06.83
Any ideas what could cause the extruder to grab the filament manually but not during an AMS load?
Thanks everyone for the replies and advice :)