high water temperature High

Glow-worm high water temperature Fault Code

Also written as HIGHWATERTEMPERATURE — same fault.

The Glow-worm high water temperature fault code means: your boiler has detected that the water inside has become dangerously hot and has shut itself down to prevent damage or overheating.. It appears on 1 Glow-worm model 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: The mains reset on/off switch is used to restart the boiler after a fault condition has occurred
Typical repair cost £120-250 (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 high water temperature fault code

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

Source

Glow-worm high water temperature 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