F19 error, furnace display flickers or resets randomly

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.

Possible Causes

Faulty internal power supply on Glow-worm PCB, Loose neutral connection, Shared circuit with heavy loads causing dips, Failing transformer or SMPS on PCB

How to Fix / Troubleshooting

Safety: Isolate power before accessing internal components.

Technician steps:

Check mains voltage stability at the appliance during operation.
Inspect internal wiring and connectors for loose or burnt contacts.
Measure low-voltage outputs from the PCB to sensors and actuators.
If internal power supply is unstable, replace the main PCB.

Repair Difficulty

Professional Required 5/5

Required Part

Main Control PCB

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