While you wait for answers, we may have found some information which could help you.
Click here for Britony 11t HeaterMy heating and hot water do not work and “A03” is flashing?
Relight pilot?
How can I fix my chaffoteaux & Maury Britony Combi SE?
chaffoteaux brittony combi se 80?
chaffoteaux calydra 80 combi boiler?
How can I fix my boiler chaffoteaux&maury?