HMS 1A00-0100-0002-0023: Debris on the Hotend Heatsink, or a Fallen Front Magnet
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HMS 1A00-0100-0002-0023 means the rack could not detect the hotend on the toolhead, and Bambu gives two specific things to check: debris on the hotend heatsink surface, and whether the front magnet has fallen off. The second one is the detail worth knowing, because a missing magnet looks like nothing at all.
Most detection faults are dirt. This one can be a part lying in the bottom of the machine.
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Look for the magnet first
With the power off, inspect the front face of the hotend for an empty recess where a small magnet should sit. Then look in the base of the printer, because a magnet that has let go is usually still inside and usually stuck to the nearest piece of steel. Finding it tells you the fault immediately.
Refitting one that has fallen out
Clean the recess and the magnet, check the orientation against another hotend before fixing anything, and use a small amount of two-part epoxy rather than a cyanoacrylate: the area runs warm and thin instant glues let go again. Let it cure fully before the machine handles the hotend.
Then the heatsink surface
Filament dust settles into heatsink fins and across the faces around them, and a film there changes what the detection reads. A soft detail brush gets between fins without bending them; compressed air finishes it. Avoid anything stiff, because a bent fin is a permanent change to the surface.
How HMS 1A00-0100-0002-0023 differs from the slot-side code
This code points at the hotend. When the dirt is in the toolhead’s own mounting slot instead, the message is HMS 1A00-0100-0002-0032, which names that slot specifically. Cleaning the wrong side of the joint is the usual wasted hour here.
If both are clean
A hotend with its magnet in place and clean surfaces that still will not register points at the presence detection circuit, which has codes of its own for open and short faults. Start with HMS 1A00-3000-0001-0040, and hotend construction is in 3D printing hotends.
HMS 1A00-0100-0002-0023 FAQ
Why does a hotend have a magnet at all?
It gives the mechanism a consistent thing to sense and locate against. Lose it and the hotend becomes invisible.
Can I use any magnet?
Match the size and thickness, and check the polarity against a known-good hotend before fixing it.
Will the printer work without it?
Not for swapping. Detection depends on it.
How do fins get dirty so fast?
Because they move air. Anything airborne in the chamber ends up in them — the machine is reviewed in the Bambu Lab H2D review.
Code prefixes do not always sort the way you expect. HMS 1A00-2100-0002-0002 carries docking wording under a fetching prefix, so the instruction text is what to follow.
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