High
A09 on Vokera Vision Combi 25C / 30C

Your boiler has detected that the temperature of the exhaust gases leaving the unit is higher than it should be, so it has shut itself down to stay safe.

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

Flue thermistor or flue thermistor counter fault / Flue thermistor over temperature

From this model's manual
Verified against the Vokera Vision Combi 25c 30c installation & service manual, page 9.
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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