Err4
Masterbuilt
Control Board Communication or Internal Fault
Display shows “Err4” and controls are unresponsive or smoker shuts off unexpectedly.
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Control board firmware error, Loose ribbon cable between display and main board, Power surge damage to control PCB, Moisture intrusion into control panel
How to Fix / Troubleshooting
Safety first: Unplug the smoker before opening the control housing.
- Power reset: Leave the smoker unplugged for at least 5 minutes to discharge internal components, then plug back in and check if Err4 clears.
- Inspect control housing: Remove the control panel cover. Look for signs of moisture, corrosion, or burnt components on the board.
- Check connectors: Reseat any ribbon cables or plug-in connectors between the display module and main control board. Ensure they are fully inserted and not bent or damaged.
- Dry the panel: If moisture is present, gently dry the area with a clean cloth and allow the panel to air dry completely before reassembly. Do not use heat guns directly on electronics.
- Replace control board if needed: If Err4 persists and there is visible damage or no response from the controls, replace the main control board assembly.
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Repair Difficulty
Hard
4/5
Required Part
Main Control Board
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