Disconnecting the Printhead (UM3/UM3X)

If our tech support team has advised you to check the printhead cable connection, please follow the following procedures. Do not disassemble the printer unless you have been instructed to do so. Make sure you are running the latest firmware as there have been updates that have gotten rid of some ER18 and ER19 errors; this error may also appear under the name "i2c error" or "printhead communication error." Please begin the cable check process with the printer powered off. If you prefer video instructions, please scroll to the bottom of the page.


  • 2mm hex head screwdriver

1. Using your 2mm hex head screw driver, unscrew the 2 long screws at the rear of the printhead, highlighted in green below.

2. Then, press your screwdriver into the slot indicated by the red arrow to remove the top-rear plastic piece--you may find a flathead screwdriver easier for this step, though your 2mm hex head will also work.


3. Press your screwdriver against the plastic flap on the front of the connector to release the printhead cable from the printhead.


Here's a clearer view of how the connector and cable fit together:


4. Take a good look at the cable to make sure all 10 wires are seated in the plastic connector. If everything looks good, go ahead and reinsert the connector back in the printhead. 

5. Press the top-rear plastic piece back into position and screw the printhead screws back in place. If possible, apply a little removable thread-locker to the ends of the screws before screwing them in. When tightening the screws, make sure that all parts of the printhead block are well aligned.

6. Power on your printer and you should be able to print. If the error persists after having reseated the cable, contact

Video Instructions:

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