Emergency
F8 on Viessmann Vitodens 100-W B1HC-19

Your boiler has safely shut down because the gas valve did not close quickly enough, requiring a Gas Safe registered engineer to inspect the gas supply and internal controls.

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, Fuel valve closes too late., Check gas train. Check both control paths. Press "Reset" (see page 50).

From this model's manual
Verified against the Viessmann/Viessmann Vitodens 100 W B1hc B1kc 19 35 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

F4View →F5View →

All 29 fault codes on the Vitodens 100-W B1HC-19

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

0C5A101830385051525859A3A9b0b7b8E3E5F0F1F2F3F4F9FAFCFdFF

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