03
Biasi
Flue Gas / Fan Fault
Display shows error 03 and the water heater will not start; fan may not run.
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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
Faulty fan motor, Blocked flue, Faulty air pressure switch, Wiring fault between fan and PCB
How to Fix / Troubleshooting
Safety: Disconnect power before removing the front panel. Do not operate the heater with the cover removed.
Steps:
- Check flue terminal: Go outside and inspect the flue outlet. Remove any visible obstructions (ice, nests, leaves). Ensure the terminal guard (if fitted) is not clogged.
- Inspect condensate drain: A blocked condensate trap can cause flue backpressure. Locate the condensate trap under the heat exchanger, remove the cap, and flush with clean water. Reassemble securely.
- Listen for fan operation: Restore power and call for hot water. If the fan does not start, isolate power again and check the fan connector for loose or corroded pins.
- Check air pressure switch tubing: Inspect the silicone tubes from the fan/combustion chamber to the air pressure switch. Ensure they are not kinked, split, or blocked with condensate. Clear or replace as needed.
Important: If the fan is seized, noisy, or does not run even with correct wiring, it must be replaced by a qualified technician. Do not bypass the air pressure switch.
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Repair Difficulty
Hard
4/5
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