High
E03 on Saunier Duval Thelia

Your boiler is currently unable to safely clear away exhaust gases, so it has stopped working to prevent any potential risks.

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.

Technical description

Air pressure switch fault

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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