BoilerFaultCodesGlow-worm F.83 Fault Code
Also written as F83 — same fault.
The Glow-worm F.83 fault code means: your boiler's computer memory has developed a technical error, meaning the internal control system cannot process instructions correctly.. It appears on 6 Glow-worm models in our database.
Technical description: EEPROM fault – electronics defective
What causes the Glow-worm F.83 fault?
This fault occurs when the boiler's internal memory chip, which stores critical operating instructions, suffers a data failure or hardware breakdown. The most common reason is an electrical surge or natural wear and tear on the circuit board's components, leaving the boiler unable to remember how to operate safely. Because the 'brain' of the appliance can no longer read its own programming, it shuts down the system entirely to prevent accidents.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Gas Safe Register →Glow-worm models that show the F.83 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Glow-worm F.83 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