What does the Glow-worm Energy F40 fault code mean?
The F40 fault code on a Glow-worm Energy boiler indicates a fault with the domestic hot water (DHW) sensor. This typically means that the sensor is either malfunctioning or has failed, preventing the boiler from properly regulating hot water temperature.
Common Causes
- Faulty DHW Sensor: The sensor may be damaged or defective, leading to incorrect temperature readings.
- Wiring Issues: Damaged or loose wiring connections to the DHW sensor can disrupt communication between the sensor and the boiler control unit.
Can I fix it myself? (DIY)
It is recommended to call a Gas Safe Engineer to diagnose and repair this fault, as it involves gas and electrical components that require professional expertise.
Estimated Repair Cost (2026 UK Prices)
The estimated repair cost for replacing a DHW sensor on a Glow-worm Energy boiler is approximately £150 to £200. This includes the cost of the part and labour, as sensor replacements typically require professional installation.