What does the Glow-worm Ultimate F46 fault code mean?
The F46 fault code on the Glow-worm Ultimate indicates a domestic hot water (DHW) temperature fault, which suggests that the boiler is unable to achieve or maintain the desired temperature for hot water. This can lead to inadequate hot water supply for taps and showers.
Common Causes
- Faulty DHW Sensor: The temperature sensor may be malfunctioning, providing incorrect readings to the boiler’s control system.
- Blocked Heat Exchanger: A blockage in the heat exchanger can prevent proper heat transfer, leading to insufficient hot water temperature.
Can I fix it myself? (DIY)
It is recommended to call a Gas Safe Engineer for this issue, as it involves gas and electrical components that require professional expertise. Attempting DIY repairs could pose safety risks.
Estimated Repair Cost (2026 UK Prices)
The estimated repair cost for resolving the F46 fault could range from £150 to £300, depending on whether the DHW sensor needs replacement or if the heat exchanger requires cleaning or replacement. This estimate includes parts and labour.