26 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
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 |
|---|---|---|
| 47-116-45 | Combi A 30 MFFI Combi A | 2005–2007 |
Appliance names and production years are taken from the UK Product Characteristics Database (the SAP/SEDBUK register). Where a GC number is also printed in this model's own manufacturer manual, both sources were checked to agree.
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Your boiler is failing to stay lit because the flame keeps going out shortly after it starts.
Your boiler's main control computer is failing to communicate properly, which has caused the system to shut down for safety.
Your boiler's main internal computer has detected a critical electronic error that is preventing it from functioning correctly.
Your boiler's main computer control panel is experiencing an internal electronic failure, which is preventing the system from operating correctly.
Your boiler has detected an issue with the ventilation system that clears exhaust gases, so it has safely stopped working to prevent any risk.
Your boiler has detected that it has become too hot and has automatically shut itself down to prevent damage.
Your boiler has failed to ignite the flame reliably and has stopped trying for your safety.
Your boiler has detected that hot water isn't moving through your heating pipes properly, so it has shut down to prevent damage.
Your boiler has detected that the water level inside the heating system is too low to operate safely.
Your boiler is currently unable to detect correctly the temperature of your hot water, which means the taps may not heat up as expected.
The boiler is unable to read the temperature of your hot water, so it has safely shut down the production of hot water to prevent overheating.
Your boiler is failing to detect that water is circulating, which prevents it from safely igniting for your heating or hot water.
Your boiler is struggling to detect the flow of water because of a faulty electronic sensor, which will prevent your heating and hot water from working correctly.
Your boiler has lost the signal from a temperature sensor that monitors the water returning to the system, meaning the unit cannot safely regulate its heat output.
Your boiler's temperature sensing probe has likely developed a fault, causing the system to misread the water temperature and shut down for safety.
Your boiler is struggling to read the temperature outside, which is usually due to a loose wire or a damaged sensor cable.
Your boiler has lost the signal from the weather sensor installed outside your home, which may cause your heating system to run less efficiently.
Your boiler has detected a flame even though it has commanded the gas supply to shut off, meaning it has safely locked itself to prevent a potential hazard.
Your boiler has lost the ability for its internal parts to talk to each other, preventing it from starting up correctly.
Your boiler's electronic brain is unable to send signals to the system components, causing the boiler to stop working completely.
Your boiler has blocked further attempts to restart itself because the reset button has been pressed too many times in a short window.
Your boiler has stopped working because the water pressure inside the heating system has dropped too low.
Your boiler is trying to start but the flame is failing to ignite or stay alight, so it has shut down as a safety precaution.
Your boiler is struggling because the gas flame is jumping away from the burner, which indicates an issue with the air supply or gas pressure balance.
Your boiler is struggling to send signals between its internal control parts, which has caused it to stop working for your own safety.
Your boiler has stopped because it thinks a safety switch connected to your underfloor heating has been triggered or disconnected.
Not faults — these are normal operating states. Tap to expand.
BoilerFaultCodes