ER04 - Safety circuit error

This error message indicates that the safety circuit of the mainboard has been activated. To prevent any electrical damage to the mainboard, all printer processes are stopped.

The Ultimaker 2+ mainboard contains two safety jumpers. The most likely cause for this error is that the jumpers are no longer properly in place. Checking the safety jumpers requires removing the bottom cover.

Caution: Make sure the 3D printer is turned off and the power cable has been disconnected before performing these steps.

Note: Always take ESD precautions when exposing the electronics at the bottom of the printer. Handling the electronics in an unsafe way can cause damage to the machine. Submit a support ticket or contact your local reseller if you do not have access to ESD precautions, such as an ESD bracelet.


Follow the steps below to check if the safety jumpers are still in place:

1. Move the build plate To remove the mainboard cover, you will need to access the bolts in the bottom panel underneath the build plate. First, manually move the build plate all the way up.
2. Turn the printer Gently place the printer on its right side. Ensure you have enough space to do so and that your workspace is clean to prevent scratching the side panel.
3. Remove the cover The mainboard is underneath the largest of the two metal covers at the bottom of the printer. Loosen the two bolts that secure the cover from the inside of the printer using the 2 mm hex key or screwdriver, while holding the lock nuts at the bottom of the printer using pliers or a (socket) wrench.
4. Locate the jumpers After removing the cover, look for SAFETY1 and SAFETY2 on the mainboard. The little black jumpers should be attached here. Try removing and reconnecting them if necessary.
UM2-Remove-mainboard-cover.jpg UM2-Mainboard-cover.jpg UM2-Mainboard-jumpers.jpg

Loosen the cover using a screwdriver and wrench


Remove the mainboard cover Locate the jumpers in the corner of the mainboard

If one of the jumpers is missing or damaged, it must be replaced. Contact your local reseller for spare parts.

Need further support?

When the error continues to appear although the jumpers are both installed correctly, the mainboard itself could be damaged. In this case, submit a ticket to contact support for further assistance.

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