What does the Glow-worm Betacom F91 fault code mean?
The F91 fault code indicates a problem with the domestic hot water (DHW) flow rate sensor in the Glow-worm Betacom boiler. This sensor is responsible for measuring the flow of water, and a fault can disrupt the boiler’s ability to provide hot water efficiently.
Common Causes
- Blocked Sensor: Debris or limescale buildup can obstruct the sensor, preventing it from accurately measuring water flow.
- Wiring Issues: Damaged or loose wiring connections to the flow rate sensor can lead to incorrect readings and trigger the fault code.
Can I fix it myself? (DIY)
It is advisable to call a Gas Safe Engineer for this issue, as it involves gas and electrical components that require professional handling. Attempting DIY repairs could be dangerous and may void your warranty.
Estimated Repair Cost (2026 UK Prices)
The estimated repair cost for fixing the F91 fault code is around £150 to £200. This includes the cost of a new flow rate sensor and labour charges for a qualified engineer to diagnose and replace the faulty part.