Bambu Lab HMS_0700_0200 — Extruder Temperature

What Does This Error Mean?

HMS_0700_0200 on a Bambu Lab printer means the hotend temperature reading is abnormal — sensor disconnected, heater failed, or overheating beyond safe limits. The print stops to protect the hotend. Power off and inspect the hotend assembly.

Affected Models

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

Common Causes

Hotend thermistor or heater cable loose at the connector
Failed thermistor (open circuit reads as no temperature)
Failed heater cartridge (no heat — bed reaches target but nozzle does not)
Hotend cooling fan failed, causing thermal runaway

How to Fix It

Power off the printer.

Switch off at the rear and unplug. Allow the hotend to cool fully — 10 minutes is sufficient.
Inspect the toolhead cable bundle.

Open the toolhead cover (usually a single Phillips screw on Bambu Lab models). Check the thermistor and heater connectors are firmly plugged into their respective sockets on the hotend PCB.
Check the hotend cooling fan.

The small fan on the hotend (separate from the part-cooling fan) cools the heat sink to prevent thermal runaway. If the fan is jammed or stopped, this can cause HMS_0700_0200 from overheating.
Power on and watch the heating curve.

Restart and start a print preheat. In Bambu Studio Live View, watch the temperature graph. A flat line means the heater is dead. Wild oscillations mean the thermistor or PID tuning is faulty.
Order a replacement hotend if needed.

Bambu Lab sells complete hotend assemblies (X1/P1: 0.4 mm hardened steel, brass, etc.) for around USD 30–60. Replacement is a 5-minute swap with a Phillips screwdriver. Persistent HMS_0700_0200 is usually fixed by a fresh hotend.

When to Call a Professional

Hotend wiring inside the toolhead is delicate. If the issue is not a loose connector externally, contact Bambu Lab support before disassembling.

Frequently Asked Questions

What is the difference between HMS_0700_0100 and HMS_0700_0200?

HMS_0700_0100 is the heatbed temperature error. HMS_0700_0200 is the hotend (extruder) temperature error. Both indicate temperature sensor or heater issues in the respective heating zone.

Can I just replace the thermistor instead of the whole hotend?

Possible but fiddly — Bambu Lab hotends are sold as complete assemblies because individual thermistor replacement requires fine soldering on the hotend PCB. For most users, the complete assembly swap is faster and more reliable.