BoilerFaultCodesYour boiler has become confused while trying to start up and has stopped working for safety reasons.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Sequence Error
What causes this fault?
This fault occurs when the boiler's internal computer detects that components are operating in the wrong order, such as the fan starting when it shouldn't or a sensor stuck in the 'on' position. It is essentially a safety conflict where the control board receives contradictory signals from the air pressure switch or the fan, causing the system to shut down to prevent an unsafe ignition. Most commonly, this is caused by a sticking internal switch or a failing electronic circuit board that can no longer coordinate the start-up sequence.
This fault is slightly more common during the first cold snaps of autumn when components that have been idle over summer, such as the fan or pressure switch, struggle to move freely again.
DIY fix possible
Locate the reset button on the control panelPress and hold the reset button for 5 secondsWait for the boiler to attempt to restartEnsure your gas supply is active by checking other gas appliances
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A boiler cover plan would cover faults like Sequence Error — no call-out fees, no surprises.
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