BoilerFaultCodesGlow-worm 06 Fault Code
The Glow-worm 06 fault code means: your boiler has detected a fault with the sensor that monitors the temperature of the water leaving the unit, meaning it cannot safely regulate heat.. It appears on 8 Glow-worm models in our database.
Technical description: HEATING THERMISTOR ON FLOW PIPE: CIRCUITS OPEN OR SHORT CIRCUIT. CHECK RESISTANCE OF THE THERMISTOR. (12500 ohms AT 20°C. 1750 ohms AT 70°C).
What causes the Glow-worm 06 fault?
This fault occurs when the internal sensor responsible for measuring the water temperature as it leaves the boiler fails or loses its connection to the main control board. The most common reason is that the sensor's internal electrical components have degraded over time or a wire has become loose, preventing the boiler from knowing if it is overheating. As a safety precaution, the system stops firing because it can no longer accurately regulate the heat level.
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 06 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Glow-worm 06 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