<p>Sometimes I use a DIY 3D printer running Marlin firmware and I have a hard time to set my heat bed temperature. when I set it to 70&nbsp;&deg;C for PLA, after a few minutes it decreases to 67&nbsp;&deg;C and I see these error:</p>

<pre><code>READ: Error:Thermal Runaway, system stopped! Heater_ID: bed
READ: Error:Printer halted. kill() called!
</code></pre>

<p>Since then the communication with printer is lost, the printing process stops and I have to reconnect to serial port... It's a disaster. I guess I need to lower the sensitivity to 3 degrees at least. I don't know how!?</p>

[{'answer_id': 10148, 'author': 'Nach0z', 'author_id': 16621, 'author_profile': 'https://3dprinting.stackexchange.com/users/16621', 'pm_score': 2, 'selected': True, 'text': "<p>I had a similar issue when printing with ABS, because my print cooling fan only activated once it got to a certain height above the bed. I'd say you need to do a PID tuning session, insulate the bottom of the bed better, and see if you can make sure your cooling fan doesn't blow air over the bed itself.</p>\n"}, {'answer_id': 19906, 'author': 'T0biasCZe', 'author_id': 35327, 'author_profile': 'https://3dprinting.stackexchange.com/users/35327', 'pm_score': 2, 'selected': False, 'text': '<p>For people from google:\nGo to configuration_adv.h in the marlin firmware source code, and search for &quot;THERMAL_PROTECTION_HYSTERESIS&quot;. Then increase the number. The number is how much degress celsius the temperature can be off before thermal runaway</p>\n'}]
['https://3dprinting.stackexchange.com/questions/9870', 'https://3dprinting.stackexchange.com', 'https://3dprinting.stackexchange.com/users/13700/']