What does the Glow-worm Flexicom F91 fault code mean?
The F91 fault code on a Glow-worm Flexicom boiler indicates that there are faulty environmental checks, which may relate to issues with the flue system or air supply. This fault prevents the boiler from operating safely and efficiently.
Common Causes
- Blocked Flue: A blockage in the flue can prevent proper ventilation, leading to safety checks failing.
- Incorrect Air Pressure: Insufficient air pressure can trigger environmental checks to fail, indicating a potential issue with the air intake.
Can I fix it myself? (DIY)
It is highly recommended to call a Gas Safe Engineer for this issue, as it involves safety checks related to gas and ventilation. Attempting to fix it yourself could pose serious risks.
Estimated Repair Cost (2026 UK Prices)
The estimated repair cost for resolving the F91 fault could range from £150 to £300, depending on whether the issue is a simple flue blockage or requires more extensive repairs to the air intake system.