BoilerFaultCodesGlow-worm F17 Fault Code
The Glow-worm F17 fault code means: your boiler is not receiving enough electrical power from your home's supply to operate safely and has shut down as a result.. It appears on 3 Glow-worm models in our database.
Technical description: Supply voltage too low (< 170V).
What causes the Glow-worm F17 fault?
This fault occurs when the electrical supply entering the boiler drops below a safe threshold, meaning there isn't enough power to run the internal sensitive components. The most common reason is an issue with your home's incoming mains electricity or a failing internal circuit board that can no longer process the voltage correctly.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Glow-worm models that show the F17 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Glow-worm F17 fault code information on this page is sourced and cross-checked against the official Glow-worm service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026