I just received my brand-new Bambu Lab H2S extruder today, and I’m running into a problem right from the start.
When trying to load filament via the AMS, the extruder tries to grab it but immediately pushes it back. It repeats this about four times and then throws an error saying the extruder is clogged — even though no filament has ever actually gone through it yet.
The only way I was able to get it to work was by manually pushing the filament into the toolhead, starting extrusion, and then quickly connecting the PTFE tube — which obviously isn’t how it should work on a brand-new device.
I’ve already checked all tubes and lengths; everything looks fine. But the extruder simply won’t pull the filament in by itself from the AMS.
Has anyone else experienced this issue with the H2S? Any ideas or solutions would be greatly appreciated.
Her a Video : Video
Thanks in advance!
First, verify that every PTFE tube is fully seated at both ends—pushed in until it bottoms out. Even a tiny gap can cause loading failures or partial clogs. Also ensure the paths to the extruder have no sharp bends or kinks. On H2D units in particular, many users have not inserted the PTFE tube deep enough into the buffer, leaving a gap that causes load failures—double-check that connection. Note that with a PTFE that is not properly seated, manual feeding may work while automatic loading fails.
Please check the buffer spring—it appears to be stuck. Release it so it can move freely; that should restore normal operation, if I’m interpreting your video correctly.
I’ve already checked all the PTFE tubes multiple times — they are fully inserted all the way until they bottom out, on both ends. I’m not very familiar with this new buffer system, as I only have experience with the X1C and the P1S, but I made sure each tube is pushed in completely.
It also makes no difference whether I use original Bambu filament spools or third-party spools — the problem happens in both cases. I’ve tried it several times.
Could you tell me how to visually confirm that a PTFE tube is actually seated correctly inside the buffer? Maybe I’m still missing something there.
Thanks for the link.
I’ve checked the page and made sure that everything is set up exactly as described in the wiki — including the buffer layout and the PTFE tubes being fully seated in the slider as shown there.
I’ve now received a brand new extruder unit and a new hotend from Bambu Lab and installed them — which was extremely complicated due to the tightly packed data cables inside.
Unfortunately, this didn’t solve the problem at all. I’m still getting exactly the same error as before.
At this point, I would really like to just exchange the whole printer 1:1. But that seems to be impossible, because I no longer have the original packaging.
Bambu Lab told me they could only send me a replacement if I buy a new printer first, use the packaging of that one to send back my current unit, and then I’d get my money back later — or I send it back in the original box, which I simply don’t have anymore.
Honestly, this is very frustrating. I bought a printer for around €1,500 that has never worked properly, and I can’t even send it back easily because nobody keeps such a massive box forever.
Anyway, I’m stuck. The problem is still there, and Bambu Lab hasn’t replied to my tickets in days, even though I’ve contacted their support multiple times again.
I’m extremely disappointed. I’ve always had good experiences with Bambu Support before, but now I really feel like I’m being left alone with a €1,500 brick.
I also had this issue, brand new H2S and had all the same problems that you had. I replaced the PTFE tube that goes from the buffer to the hot end with one that was about 2-3mm longer and it corrected by issues. Give that a try
Did you manage to fix it? I have the same problem with my brand new H2S printer. It doesn’t work with the auto-load filament, and when I try to feed it manually, it starts to print but then stops and says ‘extruder motor overload’. So I can’t print anything on it, which really sucks. I don’t know if it’s a firmware glitch or maybe an issue with the filament buffer, because it’s brand new and just doesn’t work.
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Have you checked that your PTFE tube is inserted all the way in the buffer?
It’s a common problem since the PTFE tubes go longer in these points than you might expect it to do.
If not inserted all the way in you might be able to load manually but it will stop when it feels the friction and just abort the print.
Thanks, but it’s not that — I’ve checked it, and I don’t know what or where the problem is. I think it’s just broken, but it looks like a nice printer if it would actually work.
And you are sure you see the PTFE tube through the little hole?
If so, I’m out of ideas even though I can repeat your issue by not inserting the PTFE deep enough.
Bambu lab should send the packaging material if a new printer doesn’t work. Have the customer package up the broken unit and send a replacement once received.
Same problem here. So frustrated. I have made sure that all of things were done. Pushed all tubes fully in. Tried a longer tube etc… Very frustrating because I can’t use the AMS at all. It really feels like a firmware issue because it extrudes fine after manually heating the nozzle and extruding filament to get it ready for a print.
would like to comment that I’m also having the same issue on a brand new printer. Extended the inner PTFE tube to 590mm and even 605mm and it made no difference.
Theres no bends or kinks in any of the tubes and the resistance to the buffer is minimal. Trying to print without the AMS and using the external spool lets me print with no issue.
Adding any AMS (tested AMS 1 and AMS 2 Pro) to the H2S causes this issue for me. I’ve tried using the AMS 2 on my X1C and it works with no issues. I’ve created a ticket and I suspect it’s a faulty filament buffer. To speed up the process I’ve purchased it and will update when I’ve installed it.
For everyone following along — I originally started this thread, so here’s an update on what has happened so far.
Bambu Lab sent me a completely new extruder unit, including the motor. I replaced it — no improvement.
Then I replaced the entire filament buffer, including the board — still no improvement.
I also replaced all tubes — same result.
Tried AMS1, AMS2, and AMS HT — no change either.
In the end, Bambu Lab support decided that I should return the whole printer. I’ve done that and I’m now waiting for the replacement unit.
So, it’s probably not a hardware issue with any single component. It might be software-related or something else entirely. Bambu Lab themselves haven’t found the root cause yet — otherwise, I’m sure they would have told me.
I ended up receiving and installing my filament buffer and can confirm this resolved the issue i was having. In addition to this, I have installed a longer PTFE tube (605mm) going from the buffer to the extruder. Printed several benchys and will be testing it properly throughout the weekend. Will create a proper write up once done.
