MAXTEMP Error on the Reality cr 10 3D Printer

Hello everybody :slightly_smiling_face:

My name is Emil and I’m a young adult who just got a broken 3D Printer for free. My hope was to repair it, but now I am failing at this attempt…

On the screen of my Reality cr 10 300 3D printer, there is a warning saying : Error: MAXTEMP.

So i figured out that the hotted could be broken. I replaced it with a new one, but that didn’t help. As I turned it on without having plugged in the Hotend to the printer, the same warning kept on appearing.
Does that mean it is broken on the inside? Is it completely broken or do I still have a chance to fix it? I’m willing to spend money on the repair, but I need professional help, since I am a complete amateur in this new hobby.

I hope somebody is kind enough to help me :slight_smile:

Thanks, Emil


A faulty replacement part is not unknown. You can compare the replacement to the original (for instance, measuring the resistance of the individual components) - if there’s a difference then that indicates the fault was probably in the hotend. If there’s no difference then either both are good or both are bad. To find which it is you can follow a guide such as
:pushpin:3D Printer hotend won’t heat up - Diagnosing - identify Fault - Replace Ceramic Heater Cartridge - YouTube

When you replaced the hotend, did that include the temperature sensor, or was it only the heater? The problem could be either a failure to heat, or a failure to control the heating. If both the sensor and the heater got replaced and that didn’t fix things then the problem might be in the controller board hardware (the part that reads the sensor value, or the part that drives the heater) or in the firmware (the part where the sensor data gets interpreted and acted on).

The only practical fix for a hardware issue in the controller is is to replace the controller board.
CREALITY 3D CR 10 V2 3D Printer TMC2208 ultra silent Driver Mainboard
Note that you might need to confirm the exact model - does ‘300’ refer to V3?

But before doing that, a less expensive task is to reload the controller firmware.
Creality How to Flash Firmware to CR-10 3D Printer - YouTube
Bootloader Flashing Guide - CR-10/Ender 2/Ender 3/Ender 5/X3S/X5S/Wanhao i3 - 1284p Boards - YouTube
(and many others).


Thank you so much for that answer. I will deal with it this Saturday at latest and if there is any result I will tell you. I don’t know if 300 refers to V3, but I will look it up! I switched the Hotend with the temperature sensor. That means that the problem must be in the firm- or hardware?
Thank you again Jeff :slight_smile:


Hi Emil, Welcome to the Forum!

Jeff’s points pretty much cover everything, but I’d like to throw my hat in the ring with my own advice too.

3D printer thermistors (temperature sensors) are usually NTC (negative temperature coefficient). This means that resistance goes down as temperature goes up. This may mean that you are getting a short circuit or something like that, leading your firmware to think the temperature is super high.

As Jeff said, if the resistance that you measure with a multimeter across the thermistor is what you expect (somewhere around 1k to 10k ohms), the problem may be deeper (in the motherboard)

If you end up replacing the control board, you’ll have to flash it anyway, so I’d check out Klipper and Fluidd while you’re at it.



Hello James,

I admire your knowledge, but sadly I’m not as talented as you are… I will try to understand everything. First of all I’m going to buy myself a multimeter to search the problem. Are any of you guys on Discord?
If so I would like to borrow a bit of you’re spare time to talk over the problem. I am also willing to give you cash for that service. As I mentioned I am still very young with little to no experience. Is anybody free to do so? Because I’m am very interested in learning about electronics etc. .

Thank you very very much James


Hi Emil,

You’re on the right track! That multimeter will come in handy later in life - trust me!

We don’t provide support as a paid service, but we do offer it free here!

As for Discord, the forum works well for the kind of discussion we have, with careful, considered responses that can be searched and indexed well down the line
A decent read on the topic below:



Hey James,

I’m sorry I didn’t mean to offend you. It is my first time using forums. We will stay here :slight_smile:
If you don’t mind me asking, are you hired by for this forum or are you answering me voluntarily? (I’m to young so I never came in touch with forums, sorry). And as there article said it is true that discord is more for a short term discussion while forums seem to me as a reasonable source of information and long term discussion.

One last question: If the motherboard has a malfunction, does that mean that the whole System is broken and I have to buy a new “PC”?



Hey Emil,

No offense was taken! I’m in a few discord groups myself and real-time support is cool, but searching is near impossible as every message is returned, not just a keyword in a topic, so a knowledgebase isn’t really built, and you get people asking the same questions again and again, which leads to the community getting a bit fed up with answering newbies.

Anyone on the forum with a little shield to the right of their name is a Core Electronics Employee, and part of our job is to keep projects moving over here. We handle all the deep technical stuff over here, and other things in other formats (online chats for quick questions, emails for order issues)

As for your motherboard, they are nowhere near as complex or expensive as a PC motherboard, they look something like this depending on your model:

There are basically a bunch of JST connections made from that to things like motors, thermistors, fans etc, and a few bigger screw terminals for something like a heated bed or hotend.

If you label all your cables, you should have no problem swapping it out with an identical replacement if you can find one. Definitely not worth throwing the printer out over!

I’ve killed a mainboard by shorting a fan connection once, and while painful, it wasn’t too hard to put everything back together and get it working again.

Let me know if you have more questions!


The trouble with NTC’s is that the voltage change becomes extremely marginal for a given temp change at higher temperatures. I had a similar problem on a car once where it was throwing a check engine light. Turned out to be a bad temperature sensor.

When the new one turned up I went through and plotted data for each of them by sticking them in a pot of water on the stove and heating it up. Here’s the two curves that I got:

Notice how the slight shift in curve of only a few Ohms results in a massive error in the temperature reading above 90°C. You can see how the resistance of the old (dead) sensor at 79.2°C was the same as what the new (good) sensor had at 90°C (hence the car was reading temperatures far above what they really were - enough that it was able to realise something was amiss).

I can only imagine the situation gets worse at the higher temps needed for a 3D printer hot-end, even with the clever linearising circuit in James’ graph.

PS. My point here is a bad NTC could be giving you very high readings, hence the MAX TEMP error.