About two weeks ago for some reason unbeknownst to me, one of my X1C’s just drove itself into the bed and kept running. Gouged the heck out of the textured PEI plate and bent the nozzle. And just kept running like that. Fortunately I was at home and heard the awful noise and stopped it. By the time I stopped it, and it didn’t even want to stop when I hit stop I had to power it off, the nozzle had bent a solid 15-20 degrees. (not the first time I’ve seen this happen, but the first time it was that bad) I replaced the nozzle and it went back to printing normally. A week later, it suddenly starting printing anything over about an inch tall horribly. I can print flat items and items under an inch and they are flawless. Over an inch high, it goes to ■■■■. You reach in and grab the item to take it off the plate, yes after allowing it to cool, and it will literally just fall apart. It’s like it misses entire layers of print. And I have done all the maintenance. Calibrated it 100 times.
Sounds and looks like it could be a number of things or even combinations.
From the initial failure description, I dare say that a good maintenance cylce is in order. The full recommended maintenance with particular attention to the z-lead screws and their bearings (they can pop-out even in normal rod cleaning (shows at the top) or the heat bed alignment brackets (shown under Step 2 here in the wiki) can shift during particularly heavy collisions), belt tensioning and a check regarding the need for bed tramming.
It may not be related to that at all though. Are the fans still operating as normal? Is the nozzle’s thermal paste fresh?
Or even a complete coincidence: Is your printer in a cooler location? Do you have a cold spell?
& 
Check out the release notes for the latest firmware.
So the nozzle and both sensors are new. I would find it odd that they worked for a week then suddenly just went to pot.
Yes, I have recently moved it. But the issue began occurring before it was moved. I keep my house at 66-68 degrees year round. The machine is not located near a window or door so it isn’t likely any cold air hitting it. The only change in the location would be that it no longer sits on the floor, it now sits about 4 feet high. But again, this issue happened before it was moved so I find that coincidental at most.
Here are some photos of the last fail. I watched it through the first 1.5 inches and all was well. About the time I stopped watching I guess it all went to pot again. I looked at it again at about 75% done and stopped it. Part of it had literally collapsed and fallen apart on itself while printing (the square part) The tube disintegrated when I removed it from the plate. I set it back together to show what it looked like for pictures. It makes no sense to me as it runs fine for over an inch before it goes to pot (I can’t say what I want to say given the filters here) and then it prints fine again after a brief complete failure. This is my oldest machine and has 3,235 hours on it. It’s never had an issue prior to this series of events.
I did see a thread while hunting earlier, which of course I can’t find now, that had a similar failure (the bed crash) in which the user said something about a tube above the nozzle that had bent. I mean I’m reaching here because I’ve never had a good experience with support. They always come across arrogant and seem to blame the user for anything that goes wrong. Not to mention it is the slowest, most arduous process dealing with them.
I see nothing in the last several firmware note releases that appears related to anything happening.
Question have you tried a different filament? Wondering if that might be an issue.
4 different brands and several different colors.
Polymaker, Sunlu, Overture and even Bambu’s own.
At this point I have 6 machines and they have been running nonstop for the last couple weeks in the runup to Christmas. Of course it fails when I need it most. But I think I’m going to replace the extruder unit since I have one on hand. I don’t know what else could be causing the issue. I still print smaller items on it and it prints fine. It’s only when it gets up above about 1.5 inches that it happens.
So for those interested, I replaced the Extruder assembly and it appears that has resolved the issue. At least the last 4 prints over 6 inches tall have all printed properly. So perhaps something in the extruder gets bent when the machine loses it’s mind and crashes into the plate.
I am having the same issue and I have replaced extruder heads and same issue. This used to never happen before and am unsure what is going on.
Hi! I’ve been having a problem for the past two days. At first, I was sure it was the AMS, but I’m not ruling anything out. Last Saturday, I had a clog (or so I thought), and for various reasons, I ended up replacing the extruder with a new one. Now my prints come out like this—no matter what file I use, they end up at different heights (not always the same ones). I say the most logical explanation is that it was a clog, but seeing that it’s still happening with the new extruder, I’m starting to think it’s the AMS that for some reason isn’t feeding properly or something. When I reloaded the file (after re-slicing it just in case), this time it appeared in the first few layers (at least it didn’t make me waste much filament), so what I did was set the filament to “external,” and so far it’s going well—it’s a 14-hour print, so I don’t know if that has any bearing on it. If it finishes fine as an external extruder and there’s no problem, I could say it’s 100% the AMS, but for now I’m not sure. Maybe someone can help me—I’m new to both 3D printing and this forum, so please forgive me if I’m not doing this right, but I’m a bit desperate. 
Which firmware are you running?
When i installed the latest available be 01.11.02.00 I ran a standard benchy and it seemed to me that is was printing in Ludicrous mode.
I opened a ticket with Bambu support with the following stated:
Since i updated the firmware to version 01.11.02.00 ( Firmware Download | Bambu Lab ) I get an error when printing the included files on the EMMC memory.
When i try to print the 3dBenchy Boat the printer states the following:
The current nozzle setting does not match the slicing file. Continuing to print may affect print quality. It is recommended to re-slice before starting the print.
[0500-803c 160712]
If i tell the print to ignore it is as if the print speed is set to Ludicrous as the printhead is going at a speed that I never see the printer printing at.
These files are pre-sliced and delivered with the printer. Always used the onboard benchy to test new Bambu Lab PLA filament.
I received this in response:
Dear Bambu Lab 3D printer user,
Thank you for your feedback. We have identified that this issue is related to the firmware, and our team is currently working on a fix.
We would greatly appreciate it if you could help us gather more information regarding this issue. If possible, please record a video showing the abnormal printhead speed, and ignore the issue while printing (if you’re concerned about damaging the printer, you may skip this step). Afterward, please follow the troubleshooting steps we will provide and record a second video. These two videos will help us collect more data about the problem, and we would be extremely grateful for your assistance.
In the meantime, you can try the following temporary solutions to get your printer working properly:
*Option One: Initiate printing via external storage or cloud methods (e.g., using Bambu Studio or Handy).
Option Two: Roll back the firmware to the previous version.Either of these methods should allow your printer to function normally. If you have any further questions or need additional assistance, please don’t hesitate to contact us.
Thank you again for your support and cooperation.
Best regards,
Bambu Lab Customer Support
I did further testing as they requested and sent footage back.
I received this as the last response:
Dear Bambu Lab 3D printer user,
Thank you very much for providing the information. We will forward it to our R&D department to help speed up the optimization process.
Additionally, may I ask if the two solutions we provided have resolved your issue? If you have any further questions or concerns, please don’t hesitate to contact us.
Best regards,
Bambu Lab Customer Support*
Since then have being patiently waiting for a firmware update for a now EOL printer.
There was a smartphone manufacturer that throttled the operating system performance of older models through an “update.”
Obviously not to help customers make the decision to buy a new smartphone. Oh no, of course not.
According to them, it was done solely because they assumed that the battery in the old phone might no longer be as powerful or capable of handling peak loads, so the throttling was supposedly only intended to protect the battery.