E03
Baxi
Flue Fan / Air Pressure Switch Fault
Boiler shows E03 and will not fire, fan may start briefly then stop
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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
Failed Baxi fan assembly, Blocked or restricted flue or condensate trap, Faulty air pressure switch or tubing, Wiring fault between PCB and fan/APS
How to Fix / Troubleshooting
Safety first: Do not attempt to dismantle the flue or sealed combustion chamber. Turn off power before any inspection.
User checks:
- Visually inspect the flue terminal outside for obstructions (leaves, nests, plastic bags, snow). Clear any obvious debris without altering the flue position.
- Check the condensate pipe outlet for blockages or freezing (in cold weather). If frozen, thaw gently with warm (not boiling) water and lag the pipe.
- Reset the boiler once and listen: you should hear the fan start. If there is no fan noise, or E03 reappears quickly, further diagnosis is needed.
Professional work only:
- Testing or replacing the fan, air pressure switch, flue seals, or internal condensate trap must be done by a Gas Safe engineer.
- They will check fan speed, APS operation, and verify the flue is correctly installed and not blocked internally.
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Repair Difficulty
Professional Required
5/5
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