What is Err Min Temp? What It Is and How to Fix It

Eventually, you’ll have to learn how to deal with printing errors and get more intimate with your printer. The “min temp” error is one of those common issues that you’ll encounter sooner or later, but know that everything can be fixed.

With that in mind, the “min temp” (also known as MINTEMP) error appears when the temperature reading from the hot end or print bed thermistor (resistance thermometer) is under 18℃. Remember that the 3D printer is designed to balance the loss of heat by drawing more power to the platform and/or to the hot end. Therefore, the printer comes with a safety feature as well to prevent overheating in case a thermistor breaks down. But there’s more than one source for the “min temp” error.

Let’s discuss it in more detail, learn what to look for, and figure out how to solve it.

How to spot the error

The error appears when there’s a problem with the thermistor, usually one of its cables. You’ll notice that the temperature reading becomes erratic and random. That tells us a thermistor cable is malfunctioning or broken.

Take note that there are actually two different min temp errors. One is MIN TEMP, which is related to the hot end temperature reading, and the other one is BED MIN TEMP ERROR which tells us there’s an issue with the hotbed reading.

Both of them can also be caused by a glitch in the system, in which case you can fix it with a simple printer restart. If the error returns after the restart, then the problem is most likely the thermistor cable.

Troubleshooting

The first step is to test the thermistor using a multimeter. In case you don’t know, this device is used to measure the voltage, current, and resistance, the reason why it’s also referred to as a VOM (volt-ohm milliammeter). That being said, you can see the wiring is faulty if you can’t get a reading of the resistance on the jumper connectors. Typically, you should measure the resistance of around 100 kiloohms (㏀)

If you don’t have access to a multimeter, you can check the wires by simply wiggling them. Sometimes there’s nothing wrong with them and they just come loose. Then test the temperature readings to see if there are any significant changes when you move the extruder from a side to another. If there are changes in the reading that depend on the orientation, you’ll probably have to replace the thermistor.

If you’re wondering if the motherboard is causing these issues, the chances are quite slim. But just in case, you can check by replacing the heat bed thermistor with the hot end thermistor. If your “min temp” error doesn’t switch to being a “min temp bed” error due to the switch, then there’s indeed a problem with the motherboard connector.

Step-by-Step Fixes

Before using the 3D printer, check the ambient temperature. If it’s under 20℃, you might encounter the error. On a related note, if you just received your printer and it’s cold outside, you should wait for the printer to reach room temperature. If your 3d printer is in the garage, a shed, or anywhere outside and it’s just too cold it’s a good idea to bring the machine in the house or somewhere there’s warmer temperatures.

If the issue is caused by a low room temperature, you can try to heat the hot end or the printing bed until it goes beyond the minimum required temperature. You can do that by using a hairdryer for a few minutes. If the error goes away and the printer starts printing, then you found the problem.

If the room temperature is high enough, check for a possible glitch if you haven’t already. As mentioned earlier, sometimes restarting the printer will get rid of the error. If that doesn’t work, start inspecting the thermistor as discussed.

Look for the connection between the motherboard and thermistor. Perform a physical inspection to make sure the wire is connected and the cable sleeve didn’t snap, then use a multimeter to check the resistance. You’ll have to check the manual or wiring schematic for this step because each printer is different.

Take note that the most commonly damaged section is the section of the cable that goes from the hot end thermistor to the heater block. However, if the culprit is the bed thermistor wire, check if it’s still correctly connected to the back of the heat bed. If you have to reconnect it, use Kapton tape and make sure it’s not too tight. The cable should have some slack.

Finally, if the wiring or thermistor is damaged and none of these fixes work, replace the thermistor. You can take your printer to a professional for this step or you can do it yourself with the help of the wiring schematic or a guide.

Final Thoughts

Troubleshooting and fixing errors come into play as soon as the 3D printer walks through your door. Many things can go wrong due to faulty components, wrong settings, bad wiring, or random glitches. Sometimes they’re easy to fix and other times you really have to sift through manuals, guides, videos and look for the right solution. This guide in particular should help you solve your “min temp” error, so follow it step by step. Printing errors are common and they’re not as scary as they seem to be.