HMS 0700-9400-0001-0001: Heater Temperature Sensor Fault
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HMS 0700-9400-0001-0001 means the temperature sensor of AMS heater 1 is malfunctioning, which may be due to poor connector contact. The machine is being careful with its wording: it suspects the connection before it suspects the sensor.
Without that sensor the AMS has no safe way to run a heater, so it stops drying rather than guessing.
Where to buy
Keep a probe you can trust
A set of K-type thermocouple probes gives you a reference the machine has nothing to do with. Comparing an independent probe against the reported value is the only way to know which one is wrong.
Record both at once
A four-channel thermocouple logger records the element, the air and the ambient through an entire drying cycle. A fault that only appears once the chamber is hot is invisible to a single spot reading.
Remake the joint properly
Adhesive-lined heat shrink over a repaired sensor lead seals it and gives strain relief in one step. A bare twist in a warm chamber is exactly the poor contact the message describes.
Then unplug and measure
Disconnect the sensor and measure it cold. A plausible reading means the sensor is alive and the connector is the fault, which is the outcome you want.
How HMS 0700-9400-0001-0001 differs from abnormal heating
A heater whose behaviour disagrees with its sensor is HMS 0700-8000-0001-0004. This code is the sensor reporting nothing usable at all.
The other sensor in the same box
A disconnected humidity sensor is HMS 0700-3500-0001-0002. How these parts behave is covered in printer thermistors and filament dryers.
HMS 0700-9400-0001-0001 FAQ
Why connector contact first?
Because it is far more common than a dead sensor.
Can I still feed filament?
Usually yes. Drying is what gets disabled.
Do I need a special probe?
Any K-type will do for comparison. Consistency matters more.
Does the fault come and go?
If it does, that is a connector, not a sensor.
Sensor cables fail the same way further down the path. HMS 0700-8900-0002-0004 reports an abnormal switching detection sensor on the IN-A side of the Filament Track Switch, and names that cable as the likely cause.
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