Emergency
F.694 on Viessmann Vitodens 222-F B2TF

Your boiler has detected a safety concern with its exhaust system and has shut itself down to prevent any risk of overheating or unsafe operation.

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

Burner in a fault state. Signal comparison, deviation, flue gas high limit safety cut-out.

From this model's manual
Verified against the Viessmann Vitodens 222 F B2tf installation & service manual, page 108.
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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F.690View →F.691View →F.692View →

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