High
F3 on Viessmann Vitodens 242-F FB2B

Your boiler has detected a flame signal before it has even tried to light, which stops it from starting up safely.

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

Flame signal is already present at burner start. Check the ionisation electrode and connecting cable. Press reset button R.

From this model's manual
Verified against the Viessmann/Viessmann Vitodens 242 F Fb2b 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

F4View →F5View →

All 66 fault codes on the Vitodens 242-F FB2B

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

9A9C9E9F58599294A2A4A7A8A9b0b1b4b5b7b8bAbbbCbdbEbFC1C2C3C4CdCFd6d7d8dAdbdCdddEdFE0E1E3E4E5E6E7E8EAEbECEdEEEFF0F1F2F7F8F9FAFCFdFEFF

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