HMS 0300-1E00-0001-0001: left nozzle heater short circuit
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HMS 0300-1E00-0001-0001 means the heater in the left nozzle is drawing more current than its resistance should allow, so the printer cut it off. Unlike the bed, this is a low-voltage heater and the repair is a part you can fit. On a dual-nozzle machine you also have the best diagnostic tool available: an identical healthy heater a few centimetres away.
Affected machines: H2 series. The left half stops and the right half keeps working, so single-material prints assigned to the right tool still run while you wait for a part.
Where to buy
Measure both sides, not just the bad one
A heater cartridge is a resistive element, and a healthy one reads a specific resistance. The problem with measuring only the failed side is that you have no reference for what the number should be on your machine. Measure both: the right-hand heater tells you what healthy looks like, and the left-hand reading either matches it or does not.
Then check pin to body. Any continuity between a heater pin and the metal of the block means the element has shorted to the assembly, which is conclusive and means the hotend rather than the cable.
Finally look at the cable. A pinched loom can short two conductors together and produce the same message from a healthy heater, and the toolhead loom flexes on every print.
Left nozzle will not heat and the printer reports the heater as short circuited
Shorted heater element, occasionally a pinched toolhead loom
- Power off at the wall and let both hotends cool completely.
- Unplug the left hotend at the toolhead connector and inspect the pins in both halves.
- Measure the heater resistance on the left, then on the right as a reference, and compare.
- Measure from each heater pin to the metal of the block. Any continuity means a short to the assembly.
- Inspect the toolhead loom for a pinch or chafe where it flexes.
- If the left heater measures low or shorts to the block, fit a replacement hotend assembly for your model.
Do not clear the code and retry to see if it holds. Over-current protection fired for a reason, and repeatedly energising a shorted element is how a hotend fault becomes a board fault.
The open-circuit version is left nozzle heater open circuit, and the single-nozzle equivalent is hotend heater short circuit. Our pages on the hotend and dual nozzle printers cover the hardware.
HMS 0300-1E00-0001-0001 FAQ
Can I print on the right nozzle?
For single-material jobs assigned to the right tool, yes. Anything that switches will stop.
Can I replace just the heater cartridge?
Not on these machines. The hotend is a sealed assembly, so the whole unit is the replacement.
What resistance should the heater read?
Whatever the healthy right-hand one reads. That comparison is more reliable than any figure from a forum.
Could it be the cable instead?
It can. A pinched loom shorts two conductors and looks identical from the error message, so inspect it.
LayerWalker
Print defect diagnosis, calibration procedures and parts that actually fit. Corrections welcome through the contact page.
