hot-end not heating up


My hot-end seem to fail to heat up.
After a couple of reboots, hardware and software, I am guessing the heater or something like that failed.
Any suggestions on what to do? Like, what would be the steps to get it operational again



I’m sorry to hear that! Would you mind sending in an email with the following information to

  • Order number
  • 3D printer serial number (found at the base of the electronics enclosure at the rear)
  • Contact information
  • Shipping address

If you have access to a multimeter, we can test the resistance of the heater resistor. With the printer turned off and unplugged disconnect the hot end from the wiring harness and test hot end for the proper resistance. The smaller orange wires are for the thermistor and should read ~100k at room temperature. The larger red wires are connected to the heater resistor and should read between ~4-7 Ohm.

Please let us know what you find in your email with the above information. Once we have that information we’ll be better equipped to see what kind of resolution we can offer. I’m certain we can have you up and running shortly.




Thanks for the support.
We isolated the problem with the help from your people. It’s the heater resistor that got broken
… so now I am waiting for it to be shipped from London, because I cannot find the adequate replacement at any of my local stores. (an idea for business…?!)

just to mention that Lulzbot support team is great. They were there for me every step of the way, and made sure everything goes smoothly.

Thank you

I’m having this issue now with my printer. Is it possible that setting the hot-end to too high of a temperature can damage the heat resistor or thermistor? I think I may have done this by accident. The LCD said MAXTEMP (or something similar) and the hot-end immediately started cooling down. But now it can’t heat up again at all (but the bed does).

I’m very new to all of this and don’t have experience with multimeters. I think I can buy one at a local store and will test my heat resistor and thermistor, but I don’t know how given these instructions. Is there a picture or video of how to do this test? Also, I attached a picture of my hotend and I see on the top of the metal nozzle it looks a bit caramel-colored which I fear means something burnt? Or is that a normal color? I never looked closely before.

Looks like you melted the nozzle liner. You will need to disassemble the nozzle and replace those parts before you can use it again properly.

OK, my printer is fairly new - I’ve only done about 5 prints. It is still under warranty but I have to be honest, I might have caused it. I had PLA material loaded and I think I chose to heat up to ABS temperatures by mistake in Pronterface. Is this how I may have caused my problem?

I will contact support after the new year. I wonder what specific parts I will need. I see a lot of them here:

I assume I don’t need to buy a whole new Budaschnozzle but I could be wrong. This is where I’m not sure how to start determining what smaller parts I need. I suppose I need to disassemble the Budaschnozzle.

petrock, if it didn’t get above ~240C and you just did PLA at ABS temps, you’ll be ok. PLA just gets really watery, especially at high temperatures. Customer support will be able to help you through this. It doesn’t sound like you need a new PEEK part though (which you would need if it way overheated).



Thanks, Jeff. Just a question out of curiosity - I don’t plan on trying to find out - but is there no safety to prevent too high of temperatures? If one sets the hot-end temperature in Pronterface to something outrageous - say, 500 degrees - will the TAZ 4 just go ahead and try to heat up to that temperature until it burns and shuts down?

There’s a firmware limit of 250C, If you hit that temp the printer will shut down.

OK, that’s good to know. So at 250C, would that be hot enough to cause the hot-end to melt and damage it or do I just have a faulty piece of hardware? I wonder if I somehow brought the temperature up to the max by typing in an extra digit. I wish I had been paying closer attention as to why my hot-end got so hot.

I’m out of town now but when I return I will contact support directly - I think I have to send the hot-end in for repair or replacement. I hope they will cover this but I understand if they say that this was a result of user error and not a faulty product. Live and learn, I suppose.

250c is a failure point, as the PEEK plastic insulator will soften and depending on how long it sits at that temp it can allow the lower half to fall out.

Today I used a multimeter and confirmed my heat resistor is broken. And I see here:

that exceeding 240C can damage it. I believe that’s what I’ve done. I have located instructions on how to replace the resistor here:

They look a little intimidating for this noob, but I hope to get this fixed soon.

please check out this thread, as it evolved into the main something does not heat up thread:

I posted an alternative to the green resistor here (same thread):