BoilerFaultCodesGlow-worm F.71 Fault Code
Also written as F71 — same fault.
The Glow-worm F.71 fault code means: your boiler has detected that the sensors measuring water temperature are not reading correctly or are out of sync, causing the system to shut down for safety.. It appears on 6 Glow-worm models in our database.
Technical description: Flow/return temperature sensor
What causes the Glow-worm F.71 fault?
This fault occurs when the boiler's control board notices that the two sensors measuring water temperature are giving conflicting readings or have failed completely. The most common reason is that one of these sensors has developed a fault or become unclipped, meaning the boiler can no longer safely monitor how hot the water is getting.
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 F.71 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Glow-worm F.71 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