BoilerFaultCodesYour boiler has detected a problem while trying to light the flame or keep it burning, causing it to shut down for safety.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Burner control unit blocks (fault during burner start or burner operation)
What causes this fault?
This fault occurs when the boiler's internal computer can't detect a steady flame or the spark isn't strong enough to light the gas. The most common reason is that the sensing probe inside the burner has become dirty or worn out, meaning it can't tell the boiler it is safe to keep running.
DIY fix possible
Check if other gas appliances in your home (like a hob) are working to ensure gas supplyPress the reset button or turn the boiler off and on again to clear a temporary glitchEnsure the external condensate pipe hasn't frozen if the weather is extremely cold
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 EE — no call-out fees, no surprises.
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Viessmann Vitodens Tec 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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