Jump to content
Ultimaker Community of 3D Printing Experts

Temperature sensor stuck - UM2

Recommended Posts

So I was hoping to replace the hot end on our first Ultimaker 2 during the weekend however, I stumbled upon a problem. The temperature sensor is stuck in the UM2 heaterblock.


I've tried heating it to 260C, but the sensor won't even wiggle a little, it's really really stuck in there.

@Ultimaker I really liked that the UM Original heater block had holes that poked through the entire heater block. This made it easy to remove since you could push the heater cartridge and sensor out using a screwdriver. Now the only method is to pull on the fragile wires which will break when the sensor is stuck.

Any tips on replacing a UM2 nozzle/heaterblock without replacing the temperature sensor?




  • Like 2

Share this post

Link to post
Share on other sites


Wow, so deeply seated the sleeve of the sensor, which was not with me some time ago that way. :shock:

Is this Hotend totally broken, unusable?

For better work on HotEnd I would disconnect the wiring from the MotherBoard. :idea:

Make on the narrow side of the HotEnd carefully an additional hole (3 to 4 mm with a Dremel or Proxxon, for example) near the edge region of the sleeve. Separating regions of the hole, so that a U-shaped gap on the side is formed by a larger portion of the sleeve to be more accessible. The sensor is located at the back end of the sleeve. You can with a suitable screwdriver, then the sleeve near its opening to squeeze something, so this (preferably hot) can be pushed out.

:idea: Maybe it's possible without additional drilling. Pinching the sleeve edge a bit so you can pry it out with a watchmaker's screwdriver.

Temperatures above 260 degrees will destroy the sensor presumably, please use no small burner such as a storm lighter, this mistake I made once with mounted sensor. Maybe it works better with an adjustable hot air gun, soldering iron.



Share this post

Link to post
Share on other sites

I had the same issue. By grasping the heater with locking pliers to avoid crushing it I was able to twist it to break it loose, and finally got it out. Perhaps a small amount of WD-40 could help loosen it up. (clean out thoroughly after).

In any case, when you assemble the next one, use some anti-seize compound on the heater and the sensor to keep the issue from happening again. I'm surprised that this apparently isn't part of the assembly procedure.

Perhaps this needs to be addressed by Ultimaker as an ISO 9000 quality issue...


Share this post

Link to post
Share on other sites

Gijs, I just had this same issue and broke my sensor at the leads. The sensor sheath is so far into the block I can't get it out with tweezers or pliers. Now I have a bad nozzle and a bad sensor.


I managed to get my sensor out. Used a screw about the same size as the temp sensor diameter and screwed it in tight then took some pliers and pulled the screw along with the sensor out. So thankfully I can use this nozzle still.


Share this post

Link to post
Share on other sites


same problem with my ultimaker 2. Unfortunately. After almost 2 hours of gently trying to remove it by heating up the nozzle at different temperatures i give it up finally.

Next question is where to go from here? Cut the sensor and replace it? I have no problem releasing the heating part.

I admit, the nozzle is a mess with burned filament but as i learn here, this is not something unusual to happen. So i agree, its a design flaw to make these parts that are easaly worn out to be so hard to replace.



Share this post

Link to post
Share on other sites

+1 for this problem.

I have been printing with abrasive filament, ordered a spare nozzle before and now tried to replace it as print quality has fallen off significantly

-disassembly went smooth

-heater comes out easily

-temperature sensor stuck , looked online for instructions, tried heating the block by turning the machine on and using 'Heat nozzle' (after reinserting the heater)

-tried wiggling the wire

-temperature sensor eventually came out without its metal housing, which remained in the nozzle. Sensor destroyed and nozzle unusable

Is there a better method to prevent destroying the temperature sensor each time I replace the nozzle?

I love the machine, but this is definitely a downside.


Fablab Brussels

  • Like 1

Share this post

Link to post
Share on other sites

Well there's 3 important things you can do:

1) When inserting the temp sensor into the block if it is at all tight, remove it and use a drill bit to widen the whole ever so slightly.  A 3mm drill will work fine, or a #31 drill if you are in USA.  The 3mm drill should be loose in the hole, move it around against all the walls while spinning at high speed for about 6 seconds, blow out dust, try again until the fit is perfect.  If you go too far (unlikely) add some aluminum foil.

2) Get an Olsson block: 3dsolex.com.  then you can change nozzles without changing block. 3dsolex sells cheaper temp sensors if Um won't give you a free one.

3) Add a drop of light oil when it's stuck and let it sit for a few minutes.  Heat helps (but you tried that).  Also you can drill the block from the other side with a very small diameter drill - say 1mm.  When the hole hits the temp sensor you should hopefully feel it (be careful!).  then use a paper clip to push the temp sensor out.

Edited by Guest

Share this post

Link to post
Share on other sites

Hello gr5,

thanks for the suggestions, I like all of them.

-I just ordered a 3Dsolex block, though I had enough leaky nozzles before the UM2 that I understand the design logic behind making the nozzle and block as one part. Definitely worth trying though. I need something if I want to keep playing with that colorFabb carbon filament...

-I don't need a freeby thermocouple. I'm much happier with an open-source manufacturer who sells spare parts at a reasonable profit and keeps supporting its older models, rather than one that first sends out replacement parts for free, but then removes spare parts for the Cupcakes from their store...

best -Lieven

Thx -Lieven

Share this post

Link to post
Share on other sites

I understand the design logic behind making the nozzle and block as one part.


Well you need to tighten the nozzle into the block very tight so it won't leak. But not too tight as brass isn't as strong as steel. Anders made a special torque wrench tool for this so I recommend you print the tool early on. It's about 5 inch pounds of torque (.5 newton meters).


Share this post

Link to post
Share on other sites

Thanks all. I had the exact same problem with the temp sensor getting stuck in the block. I now have a useless nozzle with the metal casing of the sensor stuck inside.

So i ordered a new sensor and now am having a little trouble reconnecting it. Where do i recconect? Do i need to completely unasseamble walls etc of the UM2? Or is there a simple way to remove the old sensor and add a new one (im ok putting the sensor in the heat block...its the other end im having trouble with.


Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Our picks

    • Ultimaker Cura | a new interface
      We're not only trying to always make Ultimaker Cura better with the usual new features and improvements we build, but we're also trying to make it more pleasant to operate. The interface was the focus for the upcoming release, from which we would already like to present you the first glance. 
        • Like
      • 114 replies
    • "Back To The Future" using Generative Design & Investment Casting
      Designing for light-weight parts is becoming more important, and I’m a firm believer in the need to produce lighter weight, less over-engineered parts for the future. This is for sustainability reasons because we need to be using less raw materials and, in things like transportation, it impacts the energy usage of the product during it’s service life.
        • Like
      • 12 replies

Important Information

Welcome to the Ultimaker Community of 3D printing experts. Visit the following links to read more about our Terms of Use or our Privacy Policy. Thank you!