BoilerFaultCodesYour boiler has failed to light because it isn't receiving enough gas or cannot sense the flame.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Interruption Of Gas Supply or Flame Failure
What causes this fault?
This fault occurs when the boiler tries to ignite multiple times but fails to establish or maintain a steady flame. The most common reasons are a temporary interruption in the gas supply, a blocked pipe, or a worn-out internal component that can no longer create a spark or detect the heat.
This fault is frequently seen during freezing winter temperatures, as the external condensate drainage pipe can freeze and back up, preventing the boiler from lighting.
DIY fix possible
Check that your gas emergency control valve is open and you have credit on your gas meterCheck if other gas appliances in your home, like a hob, are working correctlyPress and hold the 'Reset' button for five seconds to see if the boiler restartsDuring freezing weather, check if your external condensate pipe is frozen and thaw it with warm water
Find a Gas Safe engineer
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Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like E133 — no call-out fees, no surprises.
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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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