F49
Protherm
Low Voltage / Bus Communication Fault
F49 displayed, control electronics detect low supply voltage or communication error
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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
Undersized power supply, Loose mains or earth connection, External control bus wiring fault, Internal PCB power supply issue
How to Fix / Troubleshooting
Safety first: Disconnect power before inspecting wiring.
- Measure mains voltage: Confirm that voltage is within the specified range under load.
- Inspect terminal block: Tighten all connections and check for overheating.
- Check external controls: If using external controllers (eBUS, room thermostats), disconnect them temporarily to see if F49 clears.
- PCB replacement: If supply and external wiring are correct, the internal power supply on the PCB may be faulty and require board replacement.
Warning: Persistent low voltage can damage electronics; correct the supply issue before replacing parts.
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Repair Difficulty
Medium
3/5
Required Part
Main Control PCB
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