High
03 on Saunier Duval Themaclassic Plus F30E

Your boiler is struggling to clear exhaust gases or draw in fresh air properly, so it has safely shut itself down to prevent unsafe operation.

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

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 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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