Thermal runaway: what it means and what not to do
3 min read · 3DFLO, Swansea
This error is your printer's smoke alarm. It fires when the measured temperature does not respond the way the firmware expects — which is exactly what happens when a thermistor falls out of the block while the heater keeps going.
Never disable it
There are forum posts telling you to turn the protection off to get a print finished. Ignore them. The protection is the only thing standing between a loose wire and a fire.
What to check
- A missing or torn silicone sock on the heater block
- Chafed thermistor or heater wiring at the point it flexes
- A connector that has vibrated loose at the mainboard
- A part cooling fan blowing directly onto the block
If you are not confident working inside the hotend, book it in — a diagnostic and assessment is £30 and comes off the repair.
Not sure this is your problem?
Answer a few questions about what your printer is actually doing and we'll narrow it down.
Diagnose my printerStill stuck?
We repair all makes of FDM printer from our Swansea workshop. £30 diagnostic and assessment, refunded against the cost of the repair.
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