I received my P2S Combo today. Being a technician by trade, I was meticulous with the setup, but I’m facing a baffling issue with the AMS 2 Pro right out of the box. I’ve read the forums and checked the wiki, but my symptoms don’t match the usual “friction” issues.
The Issue: The AMS enters a continuous Load/Unload loop when starting a print. The filament exits the AMS, travels a few inches into the rear PTFE tube, then immediately retracts.
The “Paradox” (Why this is weird):
Insertion is Lightning Fast: When I insert a spool into any of the 4 slots, the pre-load is incredibly smooth and fast. The filament shoots through the hub and buffer effortlessly. This rules out mechanical friction or weak motors.
Feeding Fails: Despite the smooth insertion, the actual “Feed to Toolhead” sequence fails and loops.
Manual Assist: If I manually push the filament to “help” the feeder, it sometimes starts, but random jams/stops occur mid-print.
Troubleshooting already done (to save you time):
External Spool Works Perfectly: I tested the external spool passing through the exact same PTFE Buffer path. It prints perfectly. This proves the Buffer, rear PTFE, and Hotend are clear.
Installation: I verified all PTFE connections (especially the rear one). Fully seated, no sharp angles.
Filament: Using dried official Bambu Lab PLA. No knots.
Firmware: All up to date (Printer, AMS, App).
My Theory: Since the mechanics are fast and smooth (insertion works), but the logic aborts the feed, it feels like a sensor/timing defect in the AMS hub. The filament moves, but the AMS doesn’t “see” it moving fast enough and triggers a failsafe.
Has anyone experienced this specific “Fast Insertion / Failed Feed” behavior on a new unit?
Sounds like a case for a support ticket to me. I would also guess that it has to do with the sensors in the AMS hub.
Have you tried a different slot in the AMS?
For a ticket, they always want to see photos or a video. So you could already prepare one. They also want the log file.
I had issues twice and support took 2 days to answer but then they sent me replacement parts quickly without further question. As your printer is brand new, they also might offer an exchange.
On my H2D I was having some issues with loading the filament, which were solved by cutting the filament in an angle, so I suspected it was the ptfe tube. Maybe you could check the connections? cut them very straight and push it firmly
I tinkered with it until the early hours and got nowhere. I even swore at the AMS, telling it that tomorrow it was getting sent back.
This evening after work I started filming to open my ticket and now I’m completely unable to reproduce the problem — my AMS is working perfectly without me having touched anything. I don’t understand anything anymore. I just lost 5 hours on a problem that doesn’t even exist.
My guess is that you had a slight PTFE tube misalignment issue, most likely in the coupler/4in1 coupler portion. This same thing happened to me too except the system threw up an error message after 4 tries of feeding and retracting the filament. Interestingly, I could watch the filament progress in the PTFE tube all the way into the coupler unit and then emerge on the other side toward the print head. It “looked” like it made it all the way to the nozzle but apparently stopped just short. The retracted and tried again. Very confusingly, the error message said “clogged nozzle, please investigate” or something like that. Needless to say, I spent significant time messing with cleaning of nozzle until I finally pulled out the teflon tubes and re-inserted them. What do you know: “clogged nozzle” issue solved!!!