Emergency
F8 on Viessmann Vitodens 111-W

Your boiler has detected that a gas valve inside the unit is not shutting off as quickly as it should, which triggers a safety shutdown to prevent any risk.

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

Fuel valve closes too late

From this model's manual
Verified against the Viessmann Vitodens 111 W installation & service manual, page 57.
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

F4View →F9View →

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