E5
Worcester Bosch
Air Pressure / Fan Proving Fault
Boiler shows E5, may not start or may shut down during operation, often related to fan or air pressure.
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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 condensate, Faulty air pressure switch, Split or blocked air pressure tubing, Faulty fan
How to Fix / Troubleshooting
Safety first: Isolate power and gas. Flue and combustion checks must be done by a qualified engineer.
User checks:
- Check the external flue terminal for obvious obstructions and clear them.
- Ensure the condensate pipe is not frozen or blocked.
Engineer checks:
- Inspect and clear the condensate trap and pipework; refill trap with water.
- Check the air pressure switch tubing for splits, kinks, or blockages; replace tubing if degraded.
- Test the air pressure switch operation with a manometer or continuity tester while the fan runs; replace if not switching correctly.
- Verify the fan runs at correct speed and that flue is correctly installed and unobstructed.
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Repair Difficulty
Hard
4/5
Required Part
Air Pressure Switch
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