BoilerFaultCodesYour boiler has detected a general internal fault that requires a system reset or power cycle to clear.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Cleared by removing fault and/or main switch off/on.
What causes this fault?
This fault occurs when the boiler's internal computer experiences a communication error or fails to complete its safety checking sequence during startup. The most common reason is an electronic glitch within the main control board or a failure in the ignition process that prevents the burner from firing safely. It effectively means the boiler has reached a 'deadlock' where it requires a manual intervention to confirm the system is safe to try again.
DIY fix possible
Locate the main power switch for the boiler (usually a fused spur nearby) and turn it off.Wait for approximately 30 seconds.Turn the power back on and check if the flashing light stays off and the boiler fires up.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
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A boiler cover plan would cover faults like Fast flash — no call-out fees, no surprises.
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Worcester Bosch 25si and 28si is discontinued — time for a new one?
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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