BoilerFaultCodesYour boiler's pilot light is on, but the main burner is not firing up because your external heating controls are not telling the boiler to start.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Main burner fails to light, pilot burning. Additional controls not calling for heat.
What causes this fault?
This issue occurs because the boiler is waiting for a signal from your external equipment that never arrives. Even though the boiler is ready to work, the wall thermostat, timer, or a motorised valve in your airing cupboard has likely failed or reached its target temperature and isn't sending the 'start' command. It means the boiler itself is often healthy, but the system's brain or its switching components have lost communication.
This fault often surfaces during the first cold snap of autumn when controls that have been dormant all summer are suddenly required to operate.
DIY fix possible
Check that your wall thermostat is turned up higher than the current room temperature.Ensure your programmer or heating timer is set to 'On' or 'Auto'.Check if the batteries in your wireless thermostat need replacing.
Find a Gas Safe engineer
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A boiler cover plan would cover faults like C.(2) — no call-out fees, no surprises.
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Parts for discontinued models can be hard to find and expensive. A new A-rated boiler could save you money on both repairs and energy bills.
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