I have tried a complete replacement hotend. And i have tried 4 different fans.
Ok to clarify.
I was printing 12 items on one plate.
This item would print singularly but when in large multiples it would, start printing like lattice work.
Sadly i have binned the models so cant post a photo.
I then changed a complete hotend as I suspected a partial blockage. I then ran a machine self test and at that point i saw Hotend fan abnormal.
I then contacted Bambu support Who told Me To change the TH board.
Sadly just got the same error lastnight. I will have to wait until my next set to days of to start trouble shooting. Iām leaning on my hot end fan it feels a little stiff when I try to spin it.
I have got a reply from Bambu with good news. Still not fixed yet but are going to warranty any parts to get it up and running.
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Then it might be the TH board that is faulty, changed that too?
First thing i changed after the fans.
With that error the very first thing you should do is check if the cables are connect correctly by removing them and then reconnecting them.
Usually that error is the nozzle fan. Test by plugging in. If itās fine the error will go away when heating.
Even when replacing the TH board the cable can be iffy. Obliviously making sure they are well seated.
Buy yeah, throwing so many parts at a problem seems like you only asked for more. I bet youāre a little frustrated and thatās to be expected. Did you do the replacing in that state? I canāt. I have to leave it for a bit and come back.
I have been working through it methodically.
I have been asked now by Bambu the state and colour of the TH board led (static red)
And the MC board (flashing red)
I only wish my X1C would give me errors. I have replaced every board, motor, hot end, and extruder on the machine. Machine will print a file perfect 3 times in a row, using the same exact roll of filament. Start on the 4th, or 7th, no pattern to it at all, and it will start to extrude terribly half way, or 3/4 of the way through it. Gets to the point where it stops extruding completely, but no errors come up. Only thing I havenāt changed is the display.
Also, if they are those little Molex-type connectors, make sure the contacts are properly seated in the shell. Sometimes if a pin is slightly mis-aligned, instead of mating the pin pushes the female contact (and the wire) back out of the shell a bit. The tip of the pin might touch the contact on the wire and make a flaky connection or no connection at all.
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Do you live in a high humid environment?
No very dry, it definitely isnāt the filament. I can take a brand new roll and have 3 plus perfect prints right in a row. Then the next one might mess up half way through. You can actually see the filament slowing down the feed till it will actually stop sometimes, but never any errors. It should give me an out of filament error if the extruder used it up and it wasnāt fed back in. Even changed the filament sensor. Just very frustrating.
I get where your coming from and ironically my issues started with failing prints.
Whats most annoying is the simplistic questions take at least a 3 day turn around.
Like what are the lights doing on the TH board. (the board i have just changed)
Reply sent and get a reply in 3 days.
What are the lights doing on the AP board.
Reply sent and get a reply in 3 days.
Why not ask the two questions in the same reply
I am getting replies bit they are from muppets.
2026-02-18 18:29:17
Dear Bambu Lab 3D printer user,
Thank you for reaching out to our Bambu Lab Support team.
Hello, Alright, we will send you a replacement fan. Please install it and see if the issue is resolved. Since the problem hasnāt been fixed for a long time after you purchased parts yourself, we will cover the following costs. Please provide your delivery information.
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Bambu Lab Customer Support.
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2026-02-18 06:24:27
The AP board has one red light difficult to see and one red light you can see as soon a you open the AP board cover. And that one is flashing.
The hotend fan is working but it keep saying its abnormal. See attached files. It also has a short video showing its spinning fast but somewhere on the system is reporting an error.
2026-02-17 22:08:15
Dear Bambu Lab 3D printer user,
Thank you for reaching out to our Bambu Lab Support team.
Hello, We sincerely apologize for the delayed response. Our team is currently on annual leave for the Spring Festival.Sorry for the incorrect description earlier. On the X1 series, the **TH board should show a solid red light** when normal. Based on your feedback, your TH board appears to be working properly. Please check the **AP board**: is there **one solid red light and one red light flashing once per second**? You can refer to this wiki. Replacing the AP board / Application Board ā X1 Series | Bambu Lab Wiki
Has your **fan** returned to normal operation now?
Best Regards
Bambu Lab Customer Support.
2026-02-16 23:18:06
Ok having re seated the FPC cable which was actually supplied prefitted when I purchased the TH board.
I also re seated the 4 pin cable on the fan connector
As for the solid green light on the TH board, sadly it is solid red and the flashing light on the MC board is also red.
2026-02-16 20:24:10
Hi
I have an X1C but the link shows a P1
Regards Andy T
2026-02-16 19:23:33
Dear Bambu Lab 3D printer user,
Thank you for reaching out to our Bambu Lab Support team.
Hello, We sincerely apologize for the delay in your support. Our team is currently observing the Spring Festival holiday, which has resulted in slower response timesāthank you for your understanding. Regarding the issue that persists even after you replaced the $50 accessory, we would like to cover the cost of any subsequent replacement parts for you. We hope this solution meets your satisfaction. This is a special exception we have applied for, as complimentary parts are not typically provided once the device is out of warranty.
May we ask if you replaced the FPC cable along with the main board? Logically, the issue should have been resolved after replacing these components. For further troubleshooting, please follow these steps:
1. Re-seat the 4-pin connector of the hotend cooling fan on the Extruder Interface Board.
2. Re-seat the FPC cable connector on the extruder main board.
3. After doing so, please observe the ind9icator lights and let us know your findings: - Is the LED on the TH Board solid green? - Is the LED on the MC Board flashing green every 5 seconds? This information will help us check for potential short circuits.Printer Circuit Failure Troubleshooting - P1 Series | Bambu Lab Wiki
Thank you for your cooperation and understanding.
Best Regards
Bambu Lab Customer Support.
2026-02-16 18:00:52
Reply From API:
-----------------------------------------
Just a small update on the post I made yesterday.
After doing so, please observe the ind9icator lights and let us know your findings: - Is the LED on the TH Board solid green? - Is the LED on the MC Board flashing green every 5 seconds? This information will help us check for potential short circuits.
The next reply i had claims these lights should be Redā¦
Not sure if those replying actually do know more than meā¦.. I am just hoping for better service next weekā¦they have asked for my logfiles again. The ones they told me would not tell them if the TH board was broken.. Lol