BoilerFaultCodesYour boiler is struggling to light or recognize that a flame has started, causing it to shut down for safety after several failed attempts.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Flame Signal loss in safety time – try to reset the boiler after 3rd unsuccessful ignition
What causes this fault?
This fault occurs when the boiler's internal sensors fail to detect a stable flame during the startup process. The most common reasons are a worn-out ignition electrode that cannot create a spark or a buildup of carbon on the probe that monitors the flame. In some cases, a blockage in the drainage pipe or a faulty gas valve prevents the burner from staying lit safely.
This fault is more common during the first cold snap of autumn when a boiler that has been idle all summer is suddenly forced to work at high intensity.
DIY fix possible
Check if other gas appliances, like a hob, are working to ensure gas is reaching the propertyCheck that your gas meter is in credit if you use a prepay meterLocate the reset button on the control panel and press it once to attempt a restart
Find a Gas Safe engineer
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Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like 11-66 — 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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