Emergency
03 on Saunier Duval Thema F 30 E Plus

Your boiler is struggling to clear exhaust gases effectively, meaning it has shut down as a safety precaution to prevent dangerous fumes from staying inside.

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

Air fault lock

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 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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