High
F5 on Heatline Sargon

Your boiler has detected a fault with a safety sensor that monitors the temperature of the gases leaving the flue, causing it to shut down to prevent potential overheating.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

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.

What the manual says

Manufacturer manual

Combustion product (flue) temperature probe damage

From this model's manual
Verified against the Heatline Sargon 24 installation & service manual, page 26.
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 high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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