27 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
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The GC number on your boiler's data badge identifies the exact appliance and production years, as recorded in the UK Product Characteristics Database.
| GC number | Appliance (register name) | Produced |
|---|---|---|
| 41-364-14 | UNICA MAX 30S | 2021–present |
| 47-364-61 | UNICA MAX 35C | 2021–present |
| 47-364-62 | UNICA MAX 40C | 2021–present |
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Your boiler has failed to light the flame properly and has safely shut itself down to prevent gas from building up.
Your boiler has detected a flame inside when it shouldn't be there, so it has safely shut itself down to prevent a fire or gas risk.
Your boiler has detected that it is running too hot and has automatically shut itself down to prevent damage.
Your boiler has failed to ignite or stay lit because it cannot detect a flame, meaning you currently have no heating or hot water.
Your boiler has failed to light because it cannot detect a flame, likely due to a combustion or ignition issue.
Your boiler has failed to ignite or stay lit because it cannot detect a flame, meaning you currently have no heating or hot water.
Your boiler has failed to ignite because it cannot detect a flame, likely due to a combustion or sensor issue.
Your boiler has detected an issue with the internal ventilation system that removes exhaust gases, so it has shut down as a safety precaution.
Your boiler is struggling because it cannot detect enough water in the system to operate safely.
Your boiler has detected that the water pressure inside the system is currently too low to operate safely.
Your boiler is struggling to detect the flow or pressure of water moving through the system, which is preventing it from heating your home properly.
Your boiler is struggling because the electricity supply it is receiving is unstable or failing to meet the required voltage levels.
Your boiler is struggling to accurately measure the temperature of the hot water it provides, which means you likely have no hot water or the temperature is inconsistent.
Your boiler is struggling to correctly control the amount of gas it is using to heat your home, which has caused it to shut down for safety.
Your boiler is failing to detect a flame after ignition, meaning it cannot stay on to provide you with heating or hot water.
Your boiler has detected that the water inside the unit is either too hot or is not flowing correctly, causing it to shut down to prevent internal damage.
Your boiler is unable to read the temperature of the water currently circulating through its main heating system, so it has shut down as a precaution.
Your boiler has detected that the water returning to it is too hot or that the temperature difference between the water leaving and returning is abnormal, so it has shut down to prevent damage.
Your boiler has detected that it is not burning fuel correctly, which poses a serious danger of poisonous carbon monoxide escaping into your home.
Your boiler has detected that fumes are not escaping through the flue as they should, which means the system has shut down to keep your home safe.
Your boiler is failing to detect a flame, meaning it cannot safely ignite or maintain its burner to provide you with heating or hot water.
Your boiler has detected that the exhaust gases leaving the system are becoming dangerously hot, so it has shut itself down to prevent damage or overheating.
Your boiler has detected that the internal part responsible for transferring heat to your water is clogged with debris and requires a professional cleaning.
Your boiler has detected that it is not burning fuel correctly, which poses a serious risk of carbon monoxide leakage into your home.
Your boiler has detected that it is burning fuel inefficiently, which creates a safety risk due to the potential build-up of dangerous gases.
Your boiler has detected an issue with the flame detection system, meaning it cannot reliably sense if the burner is lit and has safely shut down to prevent gas buildup.
Your boiler has stopped working because it has failed to start too many times in a row, meaning it has now locked itself out for safety.
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BoilerFaultCodes