What does the Glow-worm Energy F99 fault code mean?
The F99 fault code on the Glow-worm Energy boiler indicates a communication fault related to the domestic hot water (DHW) system. This typically suggests that there is a failure in the communication between the boiler’s control board and the DHW sensor or component.
Common Causes
- Faulty DHW Sensor: A malfunctioning sensor may not relay accurate temperature readings to the control board, causing a communication error.
- Wiring Issues: Damaged or loose wiring connections between the control board and the DHW components can disrupt communication.
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 to fix it yourself could lead to safety hazards.
Estimated Repair Cost (2026 UK Prices)
The estimated repair cost for resolving the F99 fault code is around £150 to £250. This includes potential replacement of the DHW sensor and any necessary wiring repairs, which are common issues associated with this fault.