<p>Before I start, I'll give you my setup:</p>
<ul>
<li>Ender 3 Pro</li>
<li>Marlin 2.0.7.2</li>
<li>Material/Nozzle: PETG 0.4 mm @ 215 °C</li>
<li>Bed: Glass @ 80 °C</li>
<li>Default printing speed: 70 mm/s</li>
<li>Standard part cooling fan</li>
</ul>
<p>Since I've updated the Marlin FW on from factory default to 2.0.7.2, my printer stops printing and gives out an thermal runaway exception message.  Note that, after the firmware flash, I performed a PID-Tune multiple times.</p>
<p>The problem is absolutely repeatable and happens always on beginning of layer 2 (more precisely: 40 seconds after beginning layer 2). Changing PID values doesn't change anything to the moment of the error occurring.</p>
<p>I managed to run it longer by repeatedly dropping the temperature set-point and making a photo of the temperature plot. First photo is right after the initial drop from 215 to 205 °C. Second is when the temperature started rising slowly again.</p>
<p><a href="https://i.stack.imgur.com/b67wW.jpg" rel="nofollow noreferrer" title="Right after the initial drop from 215 to 205 °C"><img src="https://i.stack.imgur.com/b67wW.jpg" alt="Right after the initial drop from 215 to 205 °C" title="Right after the initial drop from 215 to 205 °C" /></a></p>
<p><a href="https://i.stack.imgur.com/BNF1j.jpg" rel="nofollow noreferrer" title="Temperature starting to rise slowly"><img src="https://i.stack.imgur.com/BNF1j.jpg" alt="Temperature starting to rise slowly" title="Temperature starting to rise slowly" /></a></p>
<p>After this temperature drop, the hotend temperature seemed to be much less stable and reached only 205 °C.</p>
<p>At Layer 12, the same thing happened again. But dropping the temperature far too low for PETG and having the &quot;same&quot; issue again, making me stop the print.</p>
<p>This problem is pretty urgent and I haven't found any suitable solution by now. Do you have any ideas of what may cause this trouble? New heaters and thermistors are on their way right now. But I fear that this is not a hardware problem since none of the components are damaged and dysfunctional, nor the moment of failure is random.</p>

[{'answer_id': 15065, 'author': 'jwagn', 'author_id': 25805, 'author_profile': 'https://3dprinting.stackexchange.com/users/25805', 'pm_score': 3, 'selected': True, 'text': "<p>It turned out, it was a faulty heater, that wasn't able to reach and maintain temperatures over 195\xa0°C in a stable manner. The order came, had a new 50\xa0W heater, thermistor and a PTFE-Bowden tube. It works just fine again, now!</p>\n"}, {'answer_id': 16290, 'author': 'Angela', 'author_id': 28364, 'author_profile': 'https://3dprinting.stackexchange.com/users/28364', 'pm_score': 1, 'selected': False, 'text': "<p>I find my Ender 3 Max has &quot;phases&quot; where each and every print will end in a thermal error, always at layer 2. During these phases, I disable retraction to keep the flow of filament constant through the hot end and into the nozzle. While my prints are a little messier than I would like, more often than not they actually finish.</p>\n<p>Another thing that helps is to lower the initial bed temperature as much as possible, or even have it at room temperature (Max has a carborundum glass bed with blue tape over the top) and raise it as the hotend moves away from the bed. I feel that layer 2 is the &quot;transition layer&quot; where the hotend is no longer using the heat from the bed to maintain its temperature, so the controller lets it have a big burst of energy to compensate for any temperature variations and more often than not gives it too much, resulting in our beloved E1 error.</p>\n<p>I may be wrong, but I would love to try a thermal camera to see if it's true!</p>\n"}, {'answer_id': 20182, 'author': 'ΜΑΝΩΛΗΣ ΜΟΥΤΣΑΚΗΣ', 'author_id': 35993, 'author_profile': 'https://3dprinting.stackexchange.com/users/35993', 'pm_score': 0, 'selected': False, 'text': '<p>Wrap all the heat system (above nozzle) with heat tape. I solved my problem with this!</p>\n'}]
['https://3dprinting.stackexchange.com/questions/15054', 'https://3dprinting.stackexchange.com', 'https://3dprinting.stackexchange.com/users/25805/']