d.88 Medium

Glow-worm d.88 Fault Code

Also written as D88 — same fault.

The Glow-worm d.88 fault code means: your boiler is struggling to detect the flow of water needed to switch on your hot water tap, meaning it cannot ignite to heat the water for your shower or taps.. It appears on 7 Glow-worm models in our database.

Book a service

This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

Technical description: Flow rate limit value for ignition in domestic hot water mode
Typical repair cost £120-220 (including labour)

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 d.88 fault code

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

Source

Glow-worm d.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