BoilerFaultCodesGlow-worm 02 Fault Code
The Glow-worm 02 fault code means: your boiler has stopped working because it cannot safely vent waste gases or confirm that the internal fan is running correctly.. It appears on 8 Glow-worm models in our database.
Technical description: Air fault, pressure switch, no power to fan
What causes the Glow-worm 02 fault?
This fault happens when the boiler's internal components can't confirm that harmful waste gases are being safely pushed out of the flue. It usually occurs because the fan has failed to start or the air pressure switch is unable to detect the correct airflow required for ignition. Without this safety confirmation, the boiler will refuse to light to prevent a buildup of dangerous fumes.
This fault can sometimes occur during periods of high winds, which can create back-pressure in the flue and interfere with the air pressure switch readings.
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 02 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Glow-worm 02 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