Last week the Ultimaker 2 gave an ominous ERROR – STOPPED TEMP SENSOR message.
After consulting Ultimaker support and measuring the resistance over the Pt100 sensor in the printer head (only 138 Ohm when heated up, which would correspond to only 100 C ) the culprit was quickly identified. Luckily the Ultimaker support page contains a very elaborate step-by-step instruction on how to replace the Pt100 sensor. Although the instruction is very clear it takes quite some time to perform all of the disassembly and subsequent assembly steps to replace the Pt100. Be also sure to replace the temperature sensor and not the heating element since they have both the same shape, the heating element is only slightly bigger.
After removing the temperature sensor with the help of some WD40 from the heatblock it is pretty clear that the sensor was, for unknown reason, completely destroyed. Replacing the Pt100 with a fresh one from the factory directly solved the problem and we are happy printing again.