ER201 - Detected nozzle temperature is invalid

If you are encountering this error, the temperature of the nozzle detected by the printer's electronics is invalid. The nozzle temperature is likely higher than allowed.

This error refers to a problem with the PT100 sensor, which measures the temperature of the nozzle. This runs between the heater block in the print head and the mainboard at the bottom of the printer. The most likely cause for this error message is a connection problem, which could either happen due to a bad connection at the main board or damage to the sensor itself.

Caution: Make sure to always turn off the Ultimaker and let the printer cool down before troubleshooting this error.

Check the print head

First, check the back of the print head. There are two sets of white wires in the heater block. As seen from the back, the thicker wires on the left are the heater wires, the thinner white wires on the right are the PT100 sensor.


Check if the PT100 sensor is properly secured in the heater block and that there are no obvious signs of damage to any of the wires. If the PT100 or the heater looks damaged, please submit a ticket or contact your local reseller for a replacement.

Check the electronics

If the wires at the print head seem fine, you can also check the connection of the PT100 sensor to the mainboard. To do this, you will have to remove the cover at the bottom of the Ultimaker.

Note: Always take ESD precautions when exposing the electronics at the bottom of the printer. Handling the electronics in an unsafe way can cause damage to the machine. Submit a support ticket or contact your local reseller if you cannot work ESD safely.

  1. Turn off the printer and disconnect the power cable
  2. Carefully place the printer on its side
  3. Remove the two small bolts that secure the bottom cover and place the cover aside
  4. Inspect the connections shown in the image below


The cable on the left is the nozzle temperature sensor. Check if this is properly inserted into the connector.

The two wires in the gray terminal on the right are the bed heater wires. Gently pull at each individual wire to check it is securely in place. If this is not the case, push open the orange latch, reinsert the wire, and push the latch closed again.

Need further support?

If the error message persists after going through the checks on this page, there may be a problem with the PT100 sensor cable or mainboard. Please contact support to receive further assistance. 

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