F9
Protherm
EEPROM / PCB Configuration Error
Boiler shows F9 and locks out, often after a power surge or wiring issue
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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
Corrupted EEPROM data on main PCB, Incorrect PCB configuration for boiler model, Electrical surge or unstable supply, Faulty main control board
How to Fix / Troubleshooting
Safety: Isolate the boiler from the mains supply before opening the control compartment.
Steps:
- Turn off power for at least 30 seconds, then restore and attempt a reset from the user interface. Sometimes a temporary glitch clears.
- If F9 persists, access the PCB and check all connectors for secure fit and signs of burning or moisture ingress.
- Verify that the PCB part number matches the boiler model. An incorrect replacement PCB can cause configuration errors.
- A qualified technician can attempt to re‑program or configure the PCB using Protherm service tools if supported.
- If re‑configuration is not possible or fails, replace the main PCB with the correct Protherm part and perform all required setup steps (gas type, output, sensor calibration).
After repair: Perform full functional tests on heating and hot water to ensure stable operation and no recurrence of F9.
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Repair Difficulty
Hard
4/5
Required Part
Main Control PCB
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