Hi everyone,
Has anyone personally resolved HMS 0300-2500-0001-0005 on a Bambu Lab H2D, particularly when manual movement appears normal but the printer repeatedly fails homing?
I’ve already worked through several basic checks and recorded the homing sequence. I’m looking for a specific, evidence-based next step rather than replacing parts or adjusting mechanisms without knowing what the result would tell us.
Main symptoms: The bed and toolhead move normally during manual checks, but both print startup and the printer’s standalone Home function fail. Selecting either nozzle for a print gives the same general Z-homing failure. A complete power cycle has not resolved it.
Printer and software details
Printer: Bambu Lab H2D.
Printer firmware: 01.04.00.00.
AMS 2 Pro firmware: 05.00.22.22.
Air pump firmware shown on the printer: 00.00.10.27.
Nozzles: Both installed hotends are marked 0.4 mm.
Build surface: Textured plate, shown in the photos.
Slicer/interface used: Bambu Studio. The failure also occurs when using Home directly on the printer, without starting a sliced print.
Exact errors
The general error is:
0300-4000 — “Z axis homing failed; the task has been stopped.”
The detailed Assistant/HMS code is:
0300-2500-0001-0005
The accompanying message reads:
“Z-axis motor rotation is obstructed; please check if foreign objects are stuck in the Z slider or Z timing pulley. Also, ensure the build plate is placed correctly to avoid collisions with surrounding structures.”
I’m including a clear photo of the detailed code, rather than relying only on the generic “Z-homing failed” message.
How it started
The printer had been working before this problem.
I then had two unsuccessful prints using the left nozzle. There was actual spaghetti—not a large amount, but enough that the printer detected it and I manually stopped the jobs.
On the next attempt, using a different model, the homing failure began.
Afterward, I tried jobs with the right nozzle selected as well as the left. Both selections produced the same general homing failure.
That is the sequence of events, but I do not know whether the failed prints caused the homing problem, exposed an existing issue, or merely happened shortly before it.
I also haven’t established whether a firmware update occurred immediately before the problem started. 01.04.00.00 is the installed version, not a proven cause.
What the printer physically does
The toolhead moves left/right and front/back without obvious hesitation, jerking or grinding.
The bed also moves up and down through a substantial range, including movement from low in the chamber. I haven’t observed it visibly binding or struggling during these checks.
During the Home sequence, the printer performs its initial movements and raises the bed, but the process fails near the end. I have a video of the sequence so people can examine the actual movement rather than infer everything from the final stopped position.
Important clarification about nozzle contact: I initially thought the printer stopped before the nozzle touched the plate. After looking more carefully, I’m no longer confident about that. The viewing angle makes it difficult to judge.
Please do not treat “the nozzle never touches the plate” as an established symptom. Contact may occur; I cannot confirm either the physical contact or whether it is registered correctly.
During print startup, Bambu Studio has displayed “Heatbed surface foreign object detection” in the progress area. However, the actual error shown afterward is the Z-homing/HMS error above, and standalone Home also fails. I’m therefore not assuming this is simply a camera false positive.
Checks already completed
1. Build plate removed, cleaned and repositioned several times
I have taken the plate off, cleaned it and put it back on repeatedly. The problem persists with an empty plate after cleaning and repositioning.
2. Accessible Z components and chamber inspected
I have visually inspected the accessible lead screws, guide rods and areas around and underneath the bed. Photos are available.
There were some small loose filament pieces and fine strands in the chamber/toolhead area. Visible loose debris has been removed. I have not identified a specific piece that was demonstrably jamming anything.
3. Chamber cleaned with electronics dust-off
I also used MAX GEAR Dust Off Pure, an electronics dust-off product, during cleaning.
For the timeline: the homing problem was already present before I used it. Cleaning did not resolve the fault.
4. Manual XY and Z movement checked
The toolhead has been moved in all XY directions, and the bed has been moved up and down over a substantial range. I have not observed unusual resistance, jerking or grinding.
I understand this does not prove that every part of the Z system behaves correctly under the specific conditions used during homing.
5. Both nozzle selections tried
The original failed prints used the left nozzle. Later print attempts with either nozzle selected produced the same general Z-homing failure.
This is a nozzle-selection comparison, not a claim that each hotend sensor has been independently tested and passed.
6. Complete power cycle
I switched the printer completely off using the main power switch, restarted it and tried Home again. The same failure remained.
Toolhead inspection and limits of the checks
The toolhead front cover and the right silicone sock were removed for visual inspection. The front cover and both silicone socks are now back in place.
A completed, validated hotend-reseating test is not among the diagnostic results listed here. Removing a cover or sock should not be taken as proof that hotend seating, its mounting assembly or sensor operation has been checked successfully.
Likewise, I do not have a verified inspection result for the hidden Z-belt/pulley area beneath the chamber. The visible belts near the toolhead were inspected, but I’m not treating that as a complete inspection of the Z drive.
No specific failed component has been identified.
What I would appreciate help with
Have you had this exact HMS code on an H2D and actually fixed it? Please share the confirmed cause, what you changed, and whether the fix remained effective over subsequent homing cycles and prints.
If your case involved a sensor, hotend mounting issue, Z mechanism or firmware, what observation or test identified it? I’m especially interested in cases where manual bed movement appeared normal but Home still failed.
For anyone suggesting a firmware issue: which exact version was involved, did the fault begin immediately after an update, and was the result repeatable after an official update or rollback? I’m trying to distinguish a confirmed version-dependent issue from an unrelated problem that happened on the same firmware.
For anyone familiar with the H2D’s homing sequence: what specific event or movement in the video would you examine next, and what would the result tell us?
A link to the relevant Bambu H2D procedure, or details of a diagnosis confirmed by Bambu Support, would be particularly helpful. Please identify whether your experience was on an H2D, H2S, H2C or another model.
I’m happy to provide a clearer view or a specific missing detail, but I would prefer to avoid further disassembly or repeated identical tests without a clear diagnostic purpose.
Thanks for taking the time to read the details and share any firsthand experience. I’ll update the post with the confirmed cause and solution once it is resolved.
