BoilerFaultCodesGlow-worm F49 Fault Code
The Glow-worm F49 fault code means: your boiler has lost communication with your thermostat or external controls because of a possible electrical wiring issue.. It appears on 1 Glow-worm model in our database.
Technical description: EBUS voltage fault | Fault in EBUS line Short circuit in EBUS connector | • Check that the eBus controls are fitted and wired correctly.
DIY fix possible
Check if any wireless receiver boxes are plugged in and have powerInspect the thermostat for low batteries and replace them if necessaryTurn the boiler power off and back on at the fused spur to see if the connection resets
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Glow-worm models that show the F49 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Glow-worm F49 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 7 July 2026