What does the Glow-worm Ultimate F65 fault code mean?
The F65 fault code on the Glow-worm Ultimate indicates a malfunction related to the domestic hot water (DHW) pressure. This typically suggests that the pressure sensor is not detecting the correct water pressure, which can affect the boiler’s ability to provide hot water.
Common Causes
- Low Water Pressure: Insufficient water pressure in the system can trigger this fault, preventing the boiler from functioning correctly.
- Faulty Pressure Sensor: A malfunctioning or damaged pressure sensor may not accurately read the water pressure, leading to the F65 error.
Can I fix it myself? (DIY)
If you are comfortable, you can check the system pressure gauge and ensure it is within the recommended range (typically 1-1.5 bar). If the pressure is low, you can top it up using the filling loop. However, if the issue persists or you suspect a faulty sensor, it is advisable to call a Gas Safe Engineer.
Estimated Repair Cost (2026 UK Prices)
The estimated cost to repair the F65 fault could range from £150 to £250, primarily depending on whether the issue is simply a pressure adjustment or requires replacement of the pressure sensor, which can be more costly.