Viessmann
Control power / display fault
Boiler display is blank or intermittently turns off, but mains power is present
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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
Loose power connector inside boiler, Faulty on/off switch, Failing control board, Internal fuse blown on Viessmann PCB
How to Fix / Troubleshooting
Safety: Isolate the boiler from mains before opening the electrical compartment.
- Check external switch and fuse: Verify that the boiler's fused spur or breaker is on and that the fuse is intact.
- Inspect internal connections: Open the electrical cover and check that the mains connector to the control board is secure.
- Look for damage: Check the control board for burn marks or swollen components. Do not touch components unnecessarily.
- Professional repair: If the display remains blank or intermittent, a technician should test the internal fuse and replace the control board if required.
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Repair Difficulty
Hard
4/5
Required Part
Main Control Board
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