BoilerFaultCodesTechnical description
Unstable flame signal error air in gas
What causes this fault?
This fault occurs when the boiler's control system detects that the flame is flickering or unstable, making it unsafe to continue operating. The most common reasons are air bubbles trapped in the gas pipework after a service or a buildup of carbon on the sensing probe that prevents it from 'seeing' the flame correctly.
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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