High
F1 on Saunier Duval Thema F 30 E Plus

Your boiler has tried to start but failed to light the flame properly, which means it has safely shut itself down to prevent gas from building up.

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

The burner lights, then goes out. The flame is not spreading across the whole burner and is not reaching the sensing electrode or no flame detected.

From this model's manual
Verified against the Saunier Duval Thema F 30 E Plus Combi 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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