A06
IVT
Air Pressure Switch / Fan Proving Fault
Boiler shows A06, fan runs but ignition sequence does not start
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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
Blocked flue or air intake, Faulty air pressure switch, Damaged or blocked pressure tubing, Fan not reaching required speed
How to Fix / Troubleshooting
Safety: Turn off power before removing the boiler case. Flue and combustion checks must be done by a qualified engineer.
Homeowner checks:
- Inspect the flue terminal outside for obstructions and remove any debris.
Technician checks:
- Inspect and clean the air pressure switch tubes for splits, kinks, or blockages; replace tubing if degraded.
- Test the air pressure switch with a manometer or continuity tester to confirm switching at the correct pressure.
- Verify that the fan reaches the commanded speed and that the PCB receives the correct feedback signal.
- Check the flue system for restrictions or incorrect installation.
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Repair Difficulty
Hard
4/5
Required Part
Air Pressure Switch
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