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HMS_0200_0200

Bambu Lab 3D Printer

Severity: Moderate

Source: OnlyErrorCodes.com — Every error code. One place.

Bambu Lab HMS 0200-0200 — Hotend Thermistor Fault Fix

What Does This Error Mean?

HMS 0200-0200 means the hotend thermistor — the temperature sensor on the heater block — is returning data the firmware can't trust.
Either it's open (broken wire), shorted, or reading way out of plausible range.
Most cases are wires that have come loose from the thermistor leads after months of cable flex.
Power off, pull the toolhead cover, and inspect the thermistor wires.

Affected Models

  • Bambu Lab X1
  • Bambu Lab X1 Carbon
  • Bambu Lab P1S
  • Bambu Lab P1P
  • Bambu Lab A1

Common Causes

  • Thermistor wire broken at the heater block (most common)
  • Thermistor connector loose at the toolhead PCB
  • Thermistor itself failed (rare)
  • Plastic glob coating the thermistor (insulating it)
  • Toolhead cable wires broken at a flex point

How to Fix It

  1. Power off and let the hotend cool.

    HMS 0200-0200 may have triggered with the hotend hot.
    Wait 15 minutes for cooling before touching anything.
    Power off completely — not standby.
    The toolhead has live circuits in standby.

  2. Remove the toolhead cover.

    Two screws hold the front cover off the toolhead on most Bambu models (X1, P1).
    Remove them and lift the cover.
    You'll see the heater block with a small two-wire thermistor poking out one side.
    Look at where those wires go — they should be intact and plugged into a small connector.

  3. Inspect the thermistor wires.

    Trace the two thin wires from the thermistor to their connector.
    Look for any visible break, crimp, or burn mark.
    Wiggle them at the connector — does the printer's home screen flash any change?
    A loose connector reseats with a firm push.

  4. Check the heater block for plastic.

    If filament has globbed onto the heater block (common on prints that fail and stick), it can coat the thermistor and insulate it from the block's actual temperature.
    Heat the block to about 220°C very briefly, then carefully scrape softened plastic off with a brass brush or wood tool.
    Don't use steel — it scratches the block.

  5. Order a replacement hotend if needed.

    If wires look fine and the block is clean but HMS 0200-0200 returns, the thermistor itself has failed.
    Bambu sells the complete hotend assembly with new thermistor for 50–80 USD.
    15 minutes to swap.
    Don't try to replace just the thermistor — they're hand-fitted at the factory.

Frequently Asked Questions

Can plastic blob damage the thermistor permanently?

Sometimes — if the blob got hot enough to melt the thermistor's insulation, the wires can short to each other or to the block.
If you've had a major spaghetti failure that buried the toolhead in molten plastic, expect to replace the hotend.
Cheaper to replace once than fight intermittent faults for weeks.

How long does a thermistor typically last?

Bambu hotend thermistors are rated for thousands of hours.
Most failures aren't from the thermistor wearing out — they're from cable flex breaking the wires near the toolhead.
If your printer has 1000+ hours of runtime, the toolhead cable bundle is also reaching end of life and may need replacement.