Troubleshooting Lexmark T63X Printhead Errors

The Lexmark T63X series printers sometimes come up with 931-935 printhead errors that are not always caused by a defective printhead, but can actually be caused by a defective cover open switch. However, this is not mentioned in the Lexmark service manual.

This is the kind of problem that could cause many repeat service calls for a technician. The error may not be related to the printhead and many times you will not see the problem when you’re onsite servicing the printer.

After replacing the printhead, the printer will run fine, which was probably an intermittent problem to start with. After running a few hundred successful test pages you’d think that the problem is solved.

A few days later, you may get a call from your customer telling you that the problem has returned.   You figure that it may possibly be a system board or a defective replacement printhead, so you change out one or both and printer works fine again. All is well.

Then, two weeks later, that dreaded call comes in again. Printhead error! Now what? Change out another printhead?  A system board? An interconnect board? Cables?

No way! Not yet.

First, check the cover open switch located on the upper hinge on the left side.
Lexmark T63X cover open switch

Make sure that the tab on the left corner of the toner is making proper contact with the lever on the microswitch so that when the toner door is closed it tells the printer that there is a toner inserted. The lever on the switch (pictured)
Lexmark T63X lever on the microswitch

either comes loose or gets bent back due to the upper cover being closed hard, or repeatedly, over time. This cover open switch is similar in design to the switch used in other T series printers, but the switch on the T63X series is not as robust as on the other models.

So what can happen in the T63X series when the printer is running, there will be some slight outward pressure pushing back on the front cover, which will move the switch lever ever so slightly and cause it to open electrically without the cover ever being opened. When this happens during mid-print, the printer will throw a printhead error instead of a cover open/insert toner message.  Obviously, this is confusing when you think you’re troubleshooting a printhead error.

We have found that the best way to confirm proper operation of this switch is to check to see exactly where, in the travel of the closing of the front cover, this switch engages.
Lexmark T63x cover open switch repair

When the printer is powered up with toner installed and the display reads “close door or insert cartridge”, hold the cover open latch in and slowly close the cover. The message should change when the cover is about one inch away from closing.
Lexmark T63x cover open switch repair

If the message does not change until the cover is all the way closed, this switch may be the cause of the printhead error.

To repair the switch the front cover needs to be removed.
Lexmark T63x cover open switch repair

so you can make sure the switch is screwed in securely.  It may have just come loose.
Lexmark T63x cover open switch repair

If you notice that the lever on the switch is bent you can manipulate the lever very carefully with small needle-nose pliers so that it activates sooner.
Lexmark T63x cover open switch repair

If the lever or switch is broken, you’ll need to replace the cover close cable, part # 56P1395.

This problem can happen with any of the T series printers, but this particular problem has been seen more with the T63X series due to the design of the switch and the switch lever itself.

Hopefully, this information will help you out when you have an intermittent printhead error that keeps coming back. Usually, solid printhead errors are caused by the printhead, system board, or an occasional defective printhead cable, (which is not very common).

Ron Marquez is a Lexmark certified printer technician and Depot Manager at Market Point. If you have a question regarding this topic or have any other printer repair related questions or topics for which you would like more information, please send an email to

5 thoughts on “Troubleshooting Lexmark T63X Printhead Errors

  1. Pingback: How To Fix Lexmark Error Printhead in Windows

  2. Pingback: Lexmark T630 Series – Gray Background on Side or Across Whole Page | Market Point's Tech Support Blog

  3. Thanks, Ron. This is cool beans info!!!! I learned something new today. Only one thing to add….. If you need a more robust switch you can use one from an earlier model. I recently used one from a T614 to repair a “Close Cover or Insert Cartridge” problem on a T630.

    I’m gonna have to get somebody to take pics for my posts…. :-()


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