Error 05 on display; appliance does not fire and may show a fan pre-purge attempt.
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
How to Fix / Troubleshooting
Safety: Isolate electrical power before opening the casing. Do not bridge or bypass safety switches.
Steps:
- Inspect silicone tubes: Locate the air pressure switch and check both tubes for splits, kinks, or water/condensate. Remove and blow through gently to clear any blockage. Refit securely.
- Check flue and fan: Ensure the flue is not obstructed and that the fan spins freely by hand (with power off). Any grinding or stiffness indicates a failing fan.
- Check electrical connections: Confirm the spade connectors on the air pressure switch are tight and free of corrosion. Reseat them one at a time.
- Reset and test: Restore power, reset the heater, and call for hot water. If error 05 persists, the switch or fan may require replacement.
Warning: Do not attempt to permanently short the air pressure switch to keep the heater running. This is unsafe and violates gas regulations.
Repair Difficulty
Required Part
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