Bambu Lab HMS error code 0300-0600-0001-0003 is a Z-axis motion fault in the 0300-0600 motion system family. The printer’s firmware detected that the Z-axis — responsible for vertical movement between print layers — did not move as commanded or encountered unexpected resistance.

What the Error Means

The Z-axis on Bambu Lab printers typically uses lead screws or ball screws for precise vertical positioning. Suffix 0001-0003 in the motion fault subgroup indicates the Z-axis stall detection or motion completion check failed. Lead screw contamination, inadequate lubrication, a bent lead screw, or a coupler that has slipped on the motor shaft are the most common physical causes. Electrical causes include a partially failed Z-axis stepper driver.

Step-by-Step Fix

1. Power off the printer. Manually rotate the Z-axis lead screws by hand (from the top or bottom of the screw, depending on printer design) to feel for rough spots, grinding, or sticking.
2. Inspect the lead screws for dried lubricant, debris, or visible damage. Wipe them clean with a lint-free cloth.
3. Apply a fresh coat of appropriate grease to the lead screw threads — use the lubricant specified in Bambu Lab maintenance documentation. Distribute by running the Z-axis manually through its full range.
4. Check the couplers connecting each lead screw to its motor shaft. A loose coupler set screw allows the shaft to slip during moves. Tighten any loose set screws with the correct hex key.
5. Inspect the Z-axis motor cables for strain or disconnection. Reseat the motor connector at the mainboard.
6. Check that the bed or gantry is not mechanically binding — ensure no printed part, filament, or foreign object is blocking vertical travel.
7. Power on and run a homing or leveling sequence to test whether the Z-axis now completes without triggering the error.

Parts Required

• Lead screw lubricant (Bambu Lab specified, or equivalent NLGI 2 grease)
• Hex key set for coupler set screws
• Replacement Z-axis lead screw or nut if mechanical damage is found

If Z-axis errors persist after lubrication and mechanical adjustment, contact Bambu Lab support to assess the stepper driver.