BoilerFaultCodesTechnical description
Unstable flame (analogue input), underfloor heating contact or gas valve fault
What causes this fault?
This fault occurs when the boiler's control board detects that the flame is flickering or unstable, making it unsafe to continue running. The most common reasons are a buildup of carbon on the sensing probes or a failing gas valve that isn't providing a steady flow of fuel to the burner.
This fault can be more frequent during the first cold snap of winter when the boiler is suddenly forced to run at maximum output for long periods, putting strain on aging gas components.
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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