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Temp not matching print head #12210 (MINI/MINI+)

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Last updated 3 months ago
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What happened?

The printer displays the message "Temp not matching - Measured temperature is not matching expected value. Check the thermistor is in contact with hotend. In case of damage, replace it." when the measured temperature is different from the temperature expected temperature for the hotend.

This can happen if any thermistor failure on the hotend causes the printer to read the temperature within 6 ºC of the target temperature, but not the target temperature itself. The heater will keep trying to heat up while the target temperature is not reached. To prevent overheating the printer generates the error.

How to fix it?

The error might indicate some issue with the wiring, either the heater or the thermistor cables are possibly damaged.

Room temperature

Check if the room where the printer is does not have a temperature below 15 ºC.

A visual inspection

Check on the hotend, where the thermistor (purple arrow) and heater (green arrow) reside, that no wires have broken off the sensor or heater themselves. While the printer is turned off, carefully try to move the wires by hand. If any of them have come detached your search is over and the part needs to be changed. It is not recommended to solder these wires, moreover, for the thermistor, it will change its resistance and thus readings. Spare parts can be found in our e-shop, or you can contact Support for assistance.

Try preheating the hotend in LCD-menu -> Settings -> Temperatures -> Nozzle to 250 ºC. After the temperature is reached, move the cables behind the print head by hand to see if the error will appear. In case the LCD main screen shows 0/0 in the hotend temperature, check the cable connections to the Buddy board.

Loosen the one screw securing the cover (circled in the picture below) and flip it open to reveal the board.

Check that all the connectors are secure in their sockets, according to the picture below. Focus on the thermistor and heater cables (blue for the print head). Though unlikely, rough shipping or handling could have shaken the heater or thermistor cables loose.

Checking the resistance

The table below describes the correct resistance for each part, as well as what scale you should set your meter to. We have another more in-depth guide on Multimeter usage. All thermistors are rated to be 100 kΩ at 25 °C. To be realistic, with a varying temperature between 20 °C and 30 °C, you can expect a wider range of readings (~85-125 kΩ) than with the heater.

There can be micro-fractures in the cable, breaking the connections only at certain positions. Therefore, try to move the cable a bit while doing the measurement and see if the value changes drastically.
Multimeter scale

Thermistors (Bed and hotend)

[80 kΩ - 125 kΩ]

200 kΩ

Hotend heater

[12.3 Ω - 15.1 Ω]

200 Ω

The part should be cold (room temperature) and unplugged when measuring the resistance!

Where to measure

For every component, there are several options, our main focus will be on the connectors. The measurement appears on the multimeter LCD as soon as the measurement probes touch the component. To obtain the correct and relevant values, this is where you need to apply the probes:

  • Thermistors: metal inserts in plastic connectors

  • Heater cables: screws holding the cables in the connector

Parts replacement guide(s)

In case you find some parts are faulty, please order them using our e-shop, then follow the service guide(s):

How to replace a hotend thermistor (MINI/MINI+)

How to replace a hotend heater (MINI/MINI+)

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