BoilerFaultCodesGlow-worm F41 Fault Code
The Glow-worm F41 fault code means: your boiler has detected an issue with the fan that safely clears exhaust gases, causing the system to shut down for safety.. It appears on 3 Glow-worm models in our database.
Technical description: Fan fault
What causes the Glow-worm F41 fault?
This fault occurs when the boiler's control board sends a command to the fan but does not receive the correct signals back to confirm it is spinning at the right speed. The most common reasons are a mechanical failure of the fan motor, a loose connection in the internal wiring, or a fault on the main circuit board that manages power to the fan.
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 F41 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Glow-worm F41 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