Your boiler has been manually reset too many times in a short window of time and has locked itself out as a safety precaution.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: 5 Boiler Resets in 15 minutes
What causes this fault?
This fault occurs when the reset button has been pressed more than five times within a fifteen-minute window. It is usually triggered because a homeowner is trying to clear a persistent underlying error, such as a flame failure or ignition problem, and the internal computer has locked the system down for safety. The boiler enters this state to prevent potential damage from repeated failed start-up attempts.
DIY fix possible
Turn the power to the boiler off at the fused spur switch (the wall switch).Wait for at least 5 minutes to allow the internal timer to reset.Turn the power back on and wait for the boiler to complete its start-up sequence without pressing the reset button.
Find a Gas Safe engineer
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A boiler cover plan would cover faults like L0C — 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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