Emergency
F.25 on Vaillant ecoFIT pure 618

Your boiler has detected that the gases it is producing are too hot to be safe, so it has automatically shut down to prevent damage.

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 switch-off: Flue gas temperature too high

From this model's manual
Verified against the Vaillant/Vaillant Ecofit Pure 825 System installation & service manual.
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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Related fault codes

F.22View →F.28View →F.29View →

All 40 fault codes on the ecoFIT pure 618

Seeing a different code? Every code this model can display, in one place.

F.00F.01F.10F.11F.12F.13F.20F.22F.23F.24F.27F.28F.29F.32F.49F.61F.62F.63F.64F.65F.67F.68F.70F.71F.72F.73F.74F.75F.76F.77F.78F.83F.84F.85F.86F.87F.88F.89F.91

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