BoilerFaultCodesYour boiler has temporarily stopped working because it failed to light or detect a flame correctly after several attempts.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Check status code (Page 52) / Boiler reset / Ignition attempts
What causes this fault?
This fault occurs when the boiler's control system senses that the water temperature is rising far too quickly, usually because the heated water cannot leave the heat exchanger fast enough. The most common reasons are a failing central heating pump that isn't circulating the water or a physical blockage caused by a build-up of sludge and debris in the pipework.
This fault is more frequent in autumn when the heating is first turned on after being dormant all summer, which can cause internal pump components to seize.
DIY fix possible
Check that your gas prepayment meter has creditEnsure other gas appliances in your home (like a hob) are workingPress the 'Reset' button (marked with a flame symbol) for one second
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 S.53 — no call-out fees, no surprises.
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Vaillant Thermocompact 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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