BoilerFaultCodesYour boiler is failing to light the gas or isn't staying lit, meaning you currently have no heating or hot water.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: No flame detected. No ionisation current after ignition (flame not detected even after 3 attempts).
What causes this fault?
This fault occurs when the boiler's control system attempts to start a fire but cannot confirm that a stable flame has been established. The most common reasons are a lack of gas reaching the burner, worn-out spark electrodes that can't bridge the gap, or a dirty internal sensor that fails to 'see' the flame even if it has lit.
This fault is frequently seen during the first cold snap of winter when components that have been idle all summer are suddenly forced to work under high demand.
DIY fix possible
Check if your gas supply is active by testing another gas appliance like a hob.Verify there is enough credit on your gas meter if you have a pre-payment account.Press the 'Reset' button on the boiler control panel for 5 seconds to attempt a restart.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like 6A — no call-out fees, no surprises.
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Worcester Bosch Highflow 400 BF 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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