BoilerFaultCodesGlow-worm P.01 Fault Code
Also written as P01 — same fault.
The Glow-worm P.01 fault code means: your boiler is currently just running a routine internal check as it starts up the heating system, so this is a normal status message rather than a breakdown.. It appears on 12 Glow-worm models in our database.
Technical description: Start up the burner at the adjustable heat input in heating mode
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Glow-worm models that show the P.01 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Glow-worm P.01 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