HMS 1A00-1100-0002-0002: Hotend Rack Coarse Homing Failed
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HMS 1A00-1100-0002-0002 means the hotend rack could not complete its coarse homing move, and Bambu asks you to check for obstructions. Homing is how the rack establishes where zero is, so until it succeeds the machine does not know where any slot actually is.
Nothing else in the swap sequence can run before this passes, which is why it fails first and loudly.
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Obstructions, as the message says
Coarse homing drives the rack to one end of its travel and expects to reach a known point. Anything in the path stops it short, and short is indistinguishable from broken as far as the machine is concerned. Clear the full range of movement with the power off, not just the area near the slots.
Then belt tension
A belt with too little tension lets the rack lag behind the motor, so the move finishes at the wrong place even with a clear path. Too much tension loads the bearings and can stall it outright. What correct feels like, and how to measure rather than guess, is in 3D printer belt tension.
Then the end point itself
Homing relies on detecting arrival. Dust or filament film on the detection point delays that signal, which reads as travel that went on too long. Clean it before assuming the sensor has failed, because the sensor failing has its own message — see HMS 1A00-3000-0001-0040.
Why HMS 1A00-1100-0002-0002 stops everything
A rack that has not homed cannot be trusted to place a hotend within a millimetre of a mount, so the machine refuses rather than guessing. That refusal is the same instinct behind the blocked-movement code HMS 1A00-0100-0002-0026, which fires during placement instead of before it.
After it homes again
Run the rack calibration before printing. Homing establishes zero; calibration establishes where the slots sit relative to it, and a machine that lost one often needs the other. The platform is described in the Bambu Lab H2D.
HMS 1A00-1100-0002-0002 FAQ
Can I home it by hand?
No, and moving it by hand while powered risks the belt. Clear the path and let the machine try again.
Does it mean the motor is failing?
Rarely. Obstruction and tension explain nearly all of these, and both are cheap to check.
Why only sometimes?
Intermittent faults point at tension or at debris that moves. A consistent failure points at a fixed obstruction.
Do I need to recalibrate afterwards?
It is worth doing, and the calibration failures have their own codes — start at HMS 1A00-1200-0002-0001.
Before homing can fail, it has to be asked for. HMS 1A00-1000-0002-0001 refuses a swap because the toolhead axes or the rack have not finished homing at all.
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