19 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 |
|---|---|---|
| 47-930-07 | COMBI C30 | 2016–present |
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Your boiler has stopped working because the fan that helps push exhaust gases out of your home is not spinning correctly or has lost power.
Your boiler has detected that the temperature sensor for your heating water is either broken or poorly connected, preventing the unit from heating up safely.
Your boiler has stopped working because the mechanical part that clears exhaust gases from the system is not spinning or communicating correctly.
Your boiler was running but the flame went out unexpectedly, causing the system to stop working for safety.
Your boiler thinks it sees a flame even though it hasn't started the gas yet, causing it to shut down for safety.
Your boiler has detected an issue with the sensor that monitors the temperature of the water leaving the unit, causing the system to shut down for safety.
Your boiler has detected that the water temperature readings are backward, suggesting a sensor error or that pipework has been connected incorrectly.
Your boiler has detected that the electricity supply coming into your home is at a dangerously high voltage and has shut down to protect its internal electronics.
Your boiler has failed to light several times and has shut down for safety, meaning you currently have no heating or hot water.
Your boiler has got too hot and has shut itself down as a safety precaution to prevent damage.
Your boiler has detected that the electricity supply coming into your home is too low for it to operate safely and has shut down to protect its internal parts.
Your boiler has lost communication with the sensor that monitors the outdoor temperature, which might make your heating less efficient.
Your boiler has switched itself off because it has detected it is getting too hot, usually caused by a lack of water flow through the system.
Your boiler's main internal computer has stopped working correctly, meaning it can no longer control the heating and hot water functions safely.
Your boiler's internal sensor for monitoring water temperature is giving an incorrect reading, meaning the system cannot safely manage your heating.
Your boiler is not turning on because it has lost communication with your wall-mounted thermostat.
Your boiler's computer brain has been replaced or reset and needs to be told which specific model it is controlling before it can start working.
Your boiler is repeatedly trying to start up but failing, causing it to shut down to protect its internal components.
Your boiler has stopped working because the water pressure inside the system is too low and needs to be topped up.
Not faults — these are normal operating states. Tap to expand.
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BoilerFaultCodes