Glow-worm · Current Glow-worm F-code boilers
F.0Flow temperature sensor interrupted
This code applies to Energy, Energy7, Ultimate3, Sustain, Betacom4. Fault codes narrow down the likely problem, but they do not replace a model-specific diagnosis.
What you can safely check
- No internal homeowner repair is safe for this fault.
- A single reset may be tried only where the model's user manual allows it.
- Arrange an engineer if the code remains or returns.
How an engineer may fix it
Test the relevant sensor or thermistor, its position, resistance, plug and wiring; repair the connection or replace the failed sensor and verify operation.
Glow-worm presents these as a general current-code guide; verify applicability in the exact appliance manual.
Manufacturer source: Glow-worm UK — Boiler Fault Codes. Checked 15 August 2026. The appliance manual and an engineer’s on-site diagnosis take precedence. Never remove the boiler case yourself.