BoilerFaultCodesYour boiler is struggling to keep the flame lit steadily, which is causing it to shut down for safety.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Unstable flame signal
What causes this fault?
This fault occurs when the boiler's control system detects that the flame is flickering or weak, meaning it cannot guarantee safe combustion. The most common reason is a worn-out sensor that can no longer 'see' the flame effectively, or an incorrect mixture of gas and air preventing a steady burn.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like F.68 — no call-out fees, no surprises.
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Could it be time for a new boiler?
If repair costs are adding up, a new energy-efficient boiler could be the smarter long-term choice.
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