F.88 High

Glow-worm F.88 Fault Code

Also written as F88 — same fault.

The Glow-worm F.88 fault code means: your boiler has detected an issue with the valve that controls the supply of gas to the burner, meaning it cannot safely start up to provide you with heating or hot water.. It appears on 17 Glow-worm models in our database.

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description: Fault:Gasvalve
Typical repair cost £250-400 (including labour)

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Avoid the next call-out bill

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Glow-worm models that show the F.88 fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Glow-worm F.88 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