[BUG REPORT] Z-axis homing failure during Cold Pull Assistant on H2S

Bambu Lab H2 Series Bambu Lab H2S
1

Hello everyone,

I am experiencing a persistent firmware bug with my brand new H2S printer.

Issue: Every time I attempt to run the “Cold Pull Assistant” from the printer’s UI, the process fails immediately at Step 1 with error code: [0300-4000 044015] (Z-axis homing failed).

Details:

  • The standard homing procedure (before printing) works perfectly fine every time, so this is not a mechanical failure or a dirty sensor.

  • The printer is running the latest firmware version 01.02.00.00.

  • This error appears to be specific to the “Cold Pull Assistant” routine, suggesting an incorrect Z-offset calculation or a logic bug in this specific firmware module.

  • The printer stops the task before the nozzle even reaches the bed for the pull sequence.

    WhatsApp Image 2026-04-14 at 5.41.35 PM
    WhatsApp Image 2026-04-14 at 5.41.35 PM897×951 158 KB

2

I can confirm this bug as I ran into it yesterday. The bed lowers and then runs the homing routine from the lower point which never completes.

Oddly enough if you run the cold pull routine again after it has failed it will work and home correctly.

@SupportAssistant

1 Like
3

Thanks for the tip, Jon! That did the trick. I was stuck in the loop of power-cycling the machine every time it failed, but running it a second time worked perfectly!

4

Thanks for tagging me. I have reported this bug to the team to check and find a solution.

3 Likes
5

I noticed the same thing.

With the latest firmware I ran it twice as you mentioned and it worked.

1 Like
6

Can confirm the issue. For me it seems to be when the heat bed is more than half way down towards the bottom. If I move it up manually higher than half way it works fine. If I start the cold pull with the bed more than half way down the bed acts as if it’s hitting the nozzle and keeps trying. Then the error pops up.

7

Have you got any feedback? I can also confirm this issue which lead me to buy new nozzles instead of coldpulling them.

8

Also got same issue, also keep getting random build plate alignment errors when its perfect fine