Hotend preheat error #31202 (CORE One) #35202 (CORE One L)…

What happened?

The printer is showing the message "Hotend preheat error: Check the print head heater and thermistor wiring for potential damage"

Error name: Hotend preheat error

Error code: #31202 (CORE One) #35202 (CORE One L) #26202 (MK4S) #13202 (MK4) #27202 (MK3.9S) #21202 (MK3.9)

This error is shown when the printer can't heat the nozzle more than 2 ºC for 20 seconds. The printer starts a safety feature that instantly stops the heating process and displays the message on the screen. The printer then waits for the user to inspect all parts and if needed fix the issue.

How to fix it?

Before accessing or manipulating any printer parts and electronic boards, ensure the printer is cooled down and switched off.

Make sure that the ambient temperature where the printer is is stable, and above 10 ºC.

This error can be caused by any damage to the hotend heater or the hotend thermistor.

Access the LoveBoard and check the heater and thermistor cables. Make sure that they are connected correctly and that there is no damage along their length.

How to access the LoveBoard left side - CORE One

Using a T10 Torx key, loosen and remove one M3x6rT bolt. Then, release the side cover.

How to access the LoveBoard left side - CORE One L

Using a 2.5mm Allen key, remove the M3x10 screw on top of the cover to release it.

How to access the LoveBoard left side - MK4/S, MK3.9/S

Slide the LoveBoard cover upward to remove it from the Nextruder

On the xBuddy board, check if the fuse that protects the extruder is not damaged.

Make sure that the Loveboard main cable is correctly connected to the xBuddy board, and not pinched.

How to access the xBuddy board - CORE One

Locate the xBuddy board case. Looking at the printer from its rear, it is the rightmost case.

Using a T10 Torx key, remove six M3x4bT bolts to release the xBuddy box cover.

The bottom larger board is the xBuddy board, while the top smaller board is the xBuddy extension board.

How to access the xBuddy board - CORE One L

Locate the Wi-Fi module on the rear panel of the printer. Using a 2.5 mm Allen key, remove the M3x14 screw. Gently pull the Wi-Fi module straight downward to remove it from the printer.

Note that the Wi-Fi module is connected to the electronics with eight spikes.

From the inside of the printer, locate on the rear side the highlighted M3x4bT bolts.

Using a T10 Torx key, remove two M3x4rT bolts to release the rear xBuddy box cover. Lift the cover to expose the xBuddy and xBuddy extension boards.

How to access the xBuddy board - MK4/S, MK3.9/S

Access the xBuddy board by loosening four M3x6 bolts.

Multimeter check

If you have a multimeter available, use this guide to check the resistance on the hotend heater and the hotend thermistor.

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16 comments

Domagoj

•

I had this error pop up quite a bit after some usage, let's say it was 15 days of printing (350-400ish hours). After checking everything i removed the head and measured resistances and both thermistor and heater were broken. No idea how it worked sometimes in the first place. I ordered new ones and replaced both, checked them beforehand, resistances within spec, right in the middle. Connected everything and started printing. Now, couple of weeks later, after not printing for about 2 weeks i am getting the issue again. It raised the alarm after 10 mins of printing. I thought maybe dust so i re-connected all the connections to the board and restarted the print. After 15 hours of printing (Right at the end) it raised the alarm again and stopped. (Fortunately it was either last layer or heating before nozzle removal so it turned out fine). I'm out of ideas what to check. Everything was fine 2 weeks ago. Anything else that can cause this? Printer and MMU3 have the latest firmware installed.

•

If the image for this page language english is missing, check other language pages, the german one has 2 pictures helping out.
In my case, Core One, I've managed somehow to swap 2 termistor cables. The imaged helped to check that both are next to each other and bingo, calibration is working.

MrBaleenTheWhale

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I've had this issue come up on my Mk4S after updating to the newest firmware (6.2.4). Tried going back to the previous firmware, followed all troubleshooting steps, but no fix.

The printer is reporting that the Nozzle temperature is at 196C at room temperature. I've not checked the thermistor resistance yet, but it's the only failure I think could still be viable. There's a way to Thermal model calibration for Mk3/+/S but not for Mk4/S. Could be useful for fixing issues like this?

Looking at getting a new thermistor, the price of shipping is more than the cost of the component itself...

Hubble

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Hello, I had the same issue, it was working on the mk4 alone (but at the edge of the hotend self test : some time failling and some time working). When I upgraded recently with the MMU3 I experimented the same symptoms as Dan. I controlled the hotend and the heater resistance was too high (15,8 ohm), not by far but out of spec. I bought a spare hot end, and now it works fine with the MMU3 ( the heater resistance was 14,1 ohm on the new one). My conclusion is that the initial hotend provided with the mk4 upgrade (from mk3s+) either had a default or was a bit damaged when I installed it.

MIC1980

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I observed the same behavior today with my MK4s with MMU3. I updated my MK4 to an MK4S a few months ago. Single prints without multicolor change run cleanly. But now I wanted to make the first print with color change today and after about 1 hour I always got the error. I can rule out technical errors as it otherwise works perfectly with normal printing. Is there a remedy in the meantime or should I contact support?