11 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
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Your boiler is making unusual noises because of trapped air, poor water circulation, or potential issues with the gas control components.
Your boiler is receiving too much gas, which is causing it to operate loudly and inefficiently.
Your boiler is receiving too much gas, which is causing it to run inefficiently and create unusual, loud noises.
Your boiler is making a loud 'roaring' or vibrating noise because the fuel-air mixture is not burning smoothly inside the unit.
Your boiler is receiving more gas than it can safely burn, leading to operation that is significantly louder than usual.
Your boiler is burning fuel at an incorrect rate, which is causing the loud noise and indicates the mixture is not balanced correctly for safe operation.
Your boiler is struggling to burn fuel cleanly due to a build-up of dust or debris inside the combustion area.
Your boiler is failing to ignite because it cannot detect or receive the gas needed to start the flame.
Your boiler is failing to ignite because it is not receiving any gas to create the flame needed for heating.
Your boiler is failing to ignite because it is not receiving a flow of gas.
Your boiler is struggling to start because there is still some air trapped in the gas pipes, preventing the pilot light from igniting.
Not faults — these are normal operating states. Tap to expand.
BoilerFaultCodes