Brother Printer Error Code 34 — What It Means & How to Fix It

What Does This Error Mean?

Brother error 34 indicates a main PCB (circuit board) failure or a hardware fault detected during self-test. This error means the printer's main board detected that something critical is not responding correctly. It can appear after a power surge, a failed firmware update, or from component wear on older machines. Sometimes a full reset clears it — but often it signals a board-level repair is needed. Don't panic yet — try the reset steps before assuming the worst.

Affected Models

Brother HL-L2350DW
Brother HL-L2370DW
Brother MFC-L2710DW
Brother MFC-L2750DW
Brother DCP-L2550DW

Common Causes

Power surge or voltage spike that corrupted the main PCB firmware
Failed firmware update that left the printer in an unstable state
Failed or shorted component on the main PCB from age or electrical stress
Laser scanner unit failure detected during the printer's startup self-test
Main motor controller fault causing the self-test to fail

How to Fix It

Turn off the printer and unplug it from the wall outlet. Wait a full 5 minutes — not just a few seconds. This fully drains any residual power from the capacitors on the main board.

A brief power cycle does not fully reset the main board. The full 5 minutes is necessary.
While the printer is unplugged, hold down the Go button (or OK button depending on your model). Continue holding it while you plug the power cord back in. Keep holding the button for 10-15 seconds after plugging in, then release.

This key-hold reset sequence forces a deeper initialization that can clear a corrupted startup state on many Brother models.
If the printer reaches the Ready state, immediately print a test page. Go to Menu > Print Reports > Printer Settings (menu path varies by model) and print the configuration page. A successful print confirms the board is functional.

If the test page prints cleanly, the error may have been caused by a transient power event. Monitor the printer for the next few days for any recurrence.
Check whether the printer recently attempted a firmware update that may have failed. If a firmware update was interrupted by a power loss or USB disconnect, the firmware can become corrupted. Visit Brother's support site, download the latest firmware for your model, and run the firmware update tool from a computer.

Brother's firmware update tool will repair corrupted firmware if the printer is in a recoverable state. If the printer won't enter update mode, a service reset may be required.
If none of the above resolves error 34, contact Brother Support at 1-877-276-8437 or take the printer to an authorized Brother service center. Provide the full model number and serial number (on the sticker on the back of the printer). Error 34 may be covered by warranty if the printer is within the standard 1-2 year warranty period.

Brother's standard warranty is 1 year. The drum unit and toner cartridge have separate page-yield-based warranties.

When to Call a Professional

Error 34 is one of the more serious Brother error codes. If the reset procedure doesn't work, the main PCB or laser scanner unit needs diagnosis. Main PCB replacement costs $80-$200 for parts plus labor. For budget printers like the HL-L2350DW (new cost $120-$150), repair may not be economically worthwhile. Get a quote before committing to repair.

Frequently Asked Questions

Is Brother error 34 always a hardware failure?

Not always. Sometimes error 34 appears after a power glitch and clears with a proper reset. Corrupted firmware from a failed update is another recoverable cause. However, if the error persists through resets and firmware repair attempts, a hardware component (PCB or laser scanner) has likely failed. Try all software fixes first before concluding it's hardware.

What is the main PCB in a Brother printer?

PCB stands for Printed Circuit Board — it's the main computer brain of the printer. The main PCB controls everything: the motors, laser, fuser, paper feeding, and the user interface. When the main PCB fails, the whole printer stops working because there's no controller to run anything. It's the most critical and expensive component to replace.

My Brother printer is out of warranty and shows error 34 — should I repair or replace it?

Compare the cost of repair to the cost of a new printer. Basic Brother monochrome laser printers cost $100-$200 new. If the repair quote is more than 50% of a new printer's cost, buying new usually makes more sense. If your printer is a multifunction model (print/copy/scan/fax) that would cost $250+ to replace, a $100-$150 repair may be worth it.