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Bambu Lab: no filament coming out of the nozzle (what to check first on any model)

Checked against the official documentation from Bambu Lab.

Technology: FDM · Brand: Bambu Lab · Symptoms: No filament comes out, Clogged nozzle or hotend · Updated on 5 November 2026

Symptom

The Bambu Lab printer does not push plastic out of the nozzle when loading or starting, or stops extruding mid-print: it keeps moving without extruding, extrudes little and unevenly, or the screen shows an HMS code.

Likely causes, from most to least likely

  1. A clogged nozzle: low-quality filament or an inconsistent diameter, leftovers of a high-temperature material, particles from fibre-filled filaments, or PLA and PETG softening in the heat of an enclosed printer.
  2. The clog is not in the nozzle but in the extruder.
  3. Nozzle temperature too low for the material, or speed too high (for example Ludicrous mode): there is no time to melt the plastic.
  4. Wet filament: materials such as PA, PC or fibre-filled ones clog more easily when damp.
  5. A worn or damaged hotend heater, if extrusion problems persist even with the right temperature.

Checks to tell which one it is

  • Check whether the screen or Bambu Handy shows an HMS code and look up its guide on the Bambu Lab wiki.
  • Heat the nozzle to the filament's temperature and extrude a little from the screen: if nothing comes out or it is hard, there is a clog.
  • Find out whether the clog is in the hotend or the extruder with Bambu Lab's procedure for your series (on the X1 and P1, with the AMS disconnected, removing the hotend and pushing a filament through by hand).
  • Measure the filament with a caliper: it must be 1.75 ± 0.03 mm.

Before you start

Before taking anything apart, cleaning or adjusting it, switch the printer off and unplug it, unless a step says otherwise, and do not touch the nozzle, the heater block or the bed until they have cooled down. If in any doubt about electricity, heat or moving parts, stop and ask a professional.

Step-by-step fix

  1. Check temperature and speed

    Check that the nozzle temperature is the one in the filament profile. If you were printing very fast (for example in Ludicrous mode), clean the nozzle and lower the speed or raise the temperature slightly before resuming.

    Check: When extruding from the screen, the filament comes out straight and steady.

    If that does not fix it: Do a cold pull (next step).

  2. Do a cold pull

    A cold pull softens the filament inside the nozzle, lets it cool until it is almost solid and pulls it out together with burnt residue and dust. Bambu Lab has the procedure for each series (A1, A2L, P1, P2S, X1, X2D and H2): follow it with the material and temperatures it gives for your model. With a fully clogged nozzle it may not be possible: clear the clog first.

    Check: The pulled tip comes out clean and filament flows from the nozzle again.

    If that does not fix it: Follow Bambu Lab's guide to unclog the nozzle or hotend of your model; if it will not clear, replace the hotend.

  3. If the clog is in the extruder

    If filament does not feed in and out of the extruder normally, switch the printer off and clean the extruder following Bambu Lab's maintenance guide for your model.

    Check: Filament loads and retracts without effort.

    If that does not fix it: Contact Bambu Lab support and send them recent printer logs.

  4. When switching from a high-temperature to a low-temperature material

    After materials such as PAHT-CF, PET-CF, PPA or PPS and before PLA, PETG or TPU: set the nozzle to 250-300 °C, unload the material by hand, load the new one so it pushes the residue out and lower the temperature step by step to 220-240 °C while extruding until it runs clean.

    Check: The new material comes out clean and steady.

    If that does not fix it: Do a cold pull.

  5. Dry the filament

    If the spool has been left out or is a moisture-sensitive material (PA, PC or fibre-filled), dry it before printing and store it in a sealed container.

    Check: The filament comes out without bubbles or jerks.

    If that does not fix it: Try another spool to rule out the filament.

Prevention

  • Use quality filament, 1.75 ± 0.03 mm, dry and stored in a sealed container.
  • With PLA and PETG in an enclosed printer, lower the bed temperature if you can and open the door or remove the top cover.
  • Do a cold pull at least once a month, especially if you switch materials often.
  • Avoid many short prints in a row: combine small parts into a single print.

Still not fixed?

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Printers it applies to

Bambu Lab's FDM printers: A1, A1 mini, A2L, H2C, H2D, H2D Pro, H2S, P1P, P1S, P2S, X1, X1 Carbon, X1E and X2D.

Official sources

This guide summarises the official documentation linked here:

This guide is general information: usi3d has summarised it from the official documentation linked here, and it may not match your model, its version or its firmware. If in doubt, follow the manual and the support of your printer's manufacturer. You decide what you do with your machine, and working on it may affect its warranty.

Products that may help

Chosen for the symptoms in this guide and the printers it applies to, not for the commission. Check that they work with your printer before buying.

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