Emergency
F25 on Glow-worm Flexicom 24c / 28c

Your boiler has detected that the gases being vented out are much hotter than they should be, so it has turned itself off to prevent overheating.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Act immediately

Turn off your boiler and stop using gas appliances. Call a Gas Safe engineer now. This fault can be dangerous if ignored.

What the manual says

Manufacturer manual

Safety shutdown: Flue gas temperature too high

From this model's manual
Verified against the Glow Worm Flexicom 24c 28c installation & service manual, page 48.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

Engineer required

This is a emergency severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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