Please read through the steps below provided by E3D and include the requested information in a new ticket. You can choose to go through us if you purchased from Tiny Machines 3D or directly through E3D. That is up to you. 

So, we can investigate this issue further please can you complete the Phase One Troubleshooting steps found below, if the issue persists once this has been done, please provide the details listed in Phase Two.
 
Phase One Troubleshooting
Before providing the below information, please ensure that the HotEnd is at ambient room temperature.
 
  • Please provide the HeaterCore Serial Number, please see the below example for its location.
  • Please provide the E3D Works Order and Batch Number located on the side of the packaging the product was sent in, please see the below example for the location of this information. 
 
 
  • Can you please provide the order number or copy of your purchase receipt/invoice for the product? If the address on the invoice is not current please provide an updated shipping address should a replacement be needed. Make sure there is a telephone number with the shipping address.
 
  • Please check and confirm that the Voltage of the HeaterCore matches the Voltage of your printer. For further details on how to do this please refer to our blog post found here: https://e3d-online.com/blogs/news/12v-vs-24v
 
  • Approximately how many hours of print time was the HeaterCore was used before experiencing the issue?
 
  • Please check and confirm if the wires between the HotEnd and Control Board are stable and do not have any loose connections
 
  • Although a PID is not required in our assembly guide we do require this step to be completed as part of the troubleshooting process. Please complete a PID Tune as the HeaterCore is much smaller than the previous style Heater Block an unstable PID Tune can make this look like an erratic sensor.
 
Further details on how to complete a PID tune for Marlin can be found here.
 
Please note that if your printer does not have the option to save to the EEPROM (such as a Prusa Mini) you will need to add this to the start GCODE section of your slicer. Please see the last note at the above link for further details.
 
If the issue persists, please move onto Phase Two Troubleshooting, and provide the requested details.
 
 
Phase Two Troubleshooting
Before providing the below information, please ensure that the HotEnd is at ambient room temperature.
 
  • Please provide the Ambient Room Temperature
 
  • Please provide the temperature reading from the HotEnd, does this reading change if you wiggle the wire near the HotEnd?
 
  • If you have access to a Multi-Meter, please can you provide the resistance reading from the thermistor with the multi-meter set to 200k. Please note the Thermistor wire is plain white as represented in the below image.
 
  • Does this reading change if you wiggle the wire near the connector? Check the connector crimps as shown below
 
 
  • Please confirm the firmware type that you are running (e.g. Marlin, RepRap or Klipper) and also confirm the thermistor setting being used.
 
Please ensure that the above requested information is provided in your reply as this is required to assist with troubleshooting the issue.
 
If you have any questions regarding this, please do not hesitate to ask.