High
F4 on Viessmann Vitodens 100-W WB1C 26kW System Boiler

Your boiler tried to light its burner but did not detect a flame, so it has stopped to stay safe, and it will need a qualified engineer to find out why.

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

Ignition, gas train or ionisation current not established. Check the ignition module connection; check the gas train (control voltage 230 V) and gas supply pressure; check the ionisation current, electrode adjustment, condensate drain and gas line for airlocks.

From this model's manual
Verified against the Viessmann/Viessmann Vitodens 100 W Wb1c 5609059 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 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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Related fault codes

F3View →F22View →

All 26 fault codes on the Vitodens 100-W WB1C 26kW System Boiler

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

5A101830385051525859A9b0b8E3E5F0F1F2F3F8F9FAFCFdFF

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