H2D: the two nozzles don't line up (shift when switching nozzles) or nozzle offset calibration fails

Symptom

In a print using both nozzles, what one nozzle prints is offset from what the other prints, like a step or a layer shift right at the nozzle change, or the nozzle offset calibration ends with an error.

Likely causes, from most to least likely

1. Nozzle offset not calibrated or out of date: because of assembly and tolerances, the real height difference (5 mm in theory) and the XY position are never exact.
2. Offset calibration sensor (the black part sticking out behind the bed) damaged, not fitted or with its cable loose.
3. Third-party hotend or a non-magnetic nozzle (for example silicon carbide), or an A1 series hotend: the sensor cannot detect them properly.
4. Hotend fitted incorrectly or with its clip open.
5. Old firmware with a calibration bug: Bambu Lab asks for 01.01.02.08 or later.
6. In the high-precision calibration: two filaments of similar colour, badly printed test lines, chamber lights switched off, or a dirty or misaligned toolhead camera.

Checks to tell which one it is

• Check whether the shift appears exactly at the nozzle change.
• Make sure you use official H2D hotends and that their clips are closed.
• Check the firmware version on the screen.
• If the high-precision calibration fails, look at the lines it printed: they should be straight and complete.

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. Calibrate the nozzle offset

   On the screen, go to Settings → Calibration and run Nozzle Offset Calibration. The two nozzles take turns touching the bed to measure height and centre over the sensor behind the bed to measure the XY offset.

   Check: Calibration finishes without an error and the next part comes out aligned.

   If that does not fix it: Check the hotends, sensor and firmware (step 3).

2. Choose the pre-print calibration

   When sending the print, the nozzle offset calibration option «Auto» runs a quick calibration and switches to the full one if it fails or the offset is large; «On» runs the full calibration on every print.

   Check: The print starts without an offset alert.

   If that does not fix it: If the sensor cannot be found or its signal is weak, the printer runs the full calibration and, if the signal stays weak, reports an error: check the sensor (next step).

3. Check hotends, sensor and firmware

   With the printer off and cold, check that the hotends are official and their clips fully closed (refit them using the H2D hotend replacement guide), that the calibration sensor is fitted and its cable connected, and update the firmware to 01.01.02.08 or later.

   Check: Calibration completes.

   If that does not fix it: If the sensor still has no signal, contact Bambu Lab support: it may be damaged internally.

4. High-precision calibration

   Prepare two filaments of clearly different colours, one dark and one light, one in each extruder (through the AMS or the external spool), and run High-Precision Nozzle Offset Calibration from Settings → Calibration: it prints a test model and the toolhead camera measures the offset. To use its result, set nozzle offset calibration to «Off» when sending the print.

   Check: Calibration finishes and the offset is gone.

   If that does not fix it: Check the colour contrast, that the plate holds the print and the nozzle is not clogged, that the chamber lights are on and that the toolhead camera is clean and correctly mounted.

Prevention

• Calibrate the nozzle offset after changing or removing a hotend.
• Use only official H2D hotends.
• Keep the toolhead camera lens clean and do not switch the chamber lights off during calibration.

Still not fixed?

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Printers it applies to

Bambu Lab H2D, H2D Pro and X2D.

Official sources

This guide summarises the official documentation linked here:

• Nozzle Offset Calibration Introduction · Bambu Lab
• H2D Pro · Bambu Lab