17 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
Replaced by: Flexicom
The fault code is already on your display
Note it down before pressing reset — resetting clears the code immediately. How to read fault codes →
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 |
|---|---|---|
| 47-047-23 | 24cxi | 2002–present |
| 47-047-24 | 30cxi | 2002–present |
| 47-047-27 | 38cxi | 2002–present |
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Your boiler is trying to start but cannot get a flame going, so it has turned itself off for safety.
Your boiler is failing to stay lit, which means it has safely shut itself down to prevent a gas buildup.
Your boiler has detected that it is getting too hot and has automatically shut itself down to prevent damage.
Your boiler is currently unable to read the temperature of the water being sent to your radiators, so it has stopped working to prevent potential overheating.
Your boiler is struggling to accurately measure the temperature of your hot water, which means it will likely stop producing hot water until the faulty sensor is replaced.
Your boiler is struggling to accurately measure the temperature of the water returning to it from your radiators, so it has shut down to prevent potential damage.
Your boiler's internal computer is having trouble communicating with its parts, causing it to shut down for safety.
Your boiler has lost internal communication between its electronic brain and the heating system, meaning it cannot operate safely or reliably.
Your boiler has detected that the water inside the heating system has become dangerously hot and has shut itself down to prevent damage or overheating.
Your boiler is struggling to shut off its flame properly after it has finished heating, which means the system has detected a safety concern and switched itself off to prevent any risk.
Your boiler has detected that the electricity supply coming into it is too weak to operate safely.
Your boiler's control panel or display is failing to communicate properly with the main computer, causing the system to stop functioning as a safety precaution.
Your boiler has lost the connection to the temperature sensor that monitors your radiators, causing it to stop heating your home as a safety precaution.
Your boiler's computer system is having trouble communicating, which means the device cannot safely operate and has shut down to protect itself.
Your boiler has detected that the water returning from your radiators is dangerously hot, which usually means the water isn't circulating around your home properly.
Your boiler has detected that the water inside is heating up too quickly, which usually means the system is struggling to circulate water properly.
Your boiler has detected that the water temperature is rising too quickly or is significantly different between the flow and return pipes, indicating a circulation problem.
Not faults — these are normal operating states. Tap to expand.
BoilerFaultCodes