HMS 0300-9300-0001-0005: chamber sensor at the heater air inlet
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HMS 0300-9300-0001-0005 means the chamber temperature is reading abnormally and points at the sensor on the heater’s air inlet side. The machine uses two sensors on this path, inlet and outlet, and comparing them is how it works out whether the heater is doing anything. Lose one and the comparison stops meaning anything.
Affected machines: X1 series. The inlet sensor sits in cooler air than the outlet one, which is why it usually outlives it. When the inlet sensor is the one reporting, that is worth noticing: it points at a connector or a lead rather than at thermal fatigue.
Where to buy
Two sensors, one comparison
The outlet sensor sees the hottest moving air in the machine and ages fastest. The inlet sensor sees chamber air on its way back to the heater and has an easier life. So when the inlet is the one misbehaving, the first suspects change: a connector that has worked loose, a lead chafed where it passes the assembly, or something that has disturbed it during maintenance.
The useful test is to measure both. Two sensors in the same machine at room temperature should read close to each other, typically around 100k ohm. If the outlet reads sensibly and the inlet does not, you have both confirmed the fault and located it without guessing.
When you fit a replacement, put it exactly where the original sat. The firmware compares inlet and outlet expecting a particular geometry, and a sensor mounted somewhere convenient reads a different temperature and produces a new, subtler wrong answer.
Chamber temperature reads implausibly and the printer points at the air inlet sensor
Loose connector, a chafed lead, or a failed inlet sensor
- Power off at the wall and let the chamber cool completely before opening it.
- Locate the inlet sensor on the chamber heater path and note exactly how it is mounted.
- Unplug it and measure across the pins. Around 100k ohm cold is healthy.
- Measure the outlet sensor the same way and compare the two readings.
- Inspect the inlet lead and connector for chafing, a pulled pin or damage from maintenance.
- Fit the correct replacement in exactly the original position, then run a chamber preheat and watch both readings rise together.
Watch both numbers during the preheat, not just the one that was faulty. The point of two sensors is the difference between them, and a healthy system shows the outlet climbing ahead of the inlet.
The outlet version is chamber sensor at the air outlet, and the open-circuit case is chamber sensor open circuit. Our pages on enclosed printers and ABS and ASA explain what the chamber is for.
HMS 0300-9300-0001-0005 FAQ
Which sensor is this?
The one on the air inlet side of the chamber heater, not the outlet sensor and not a nozzle or bed thermistor.
What should it read?
Around 100k ohm cold, and close to whatever the outlet sensor reads at the same room temperature.
Can I print meanwhile?
PLA and PETG, yes. Chamber materials should wait until the reading is trustworthy.
Why does the inlet sensor fail less often?
Because it lives in cooler air. When it does fail, suspect the connector or the lead before the sensor.
LayerWalker
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