61 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 |
|---|---|---|
| 47-077-51 | 424 COMBI 2 | 2023–present |
| 47-077-52 | 430 COMBI 2 | 2023–present |
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Your boiler is struggling to read the temperature from the solar heating connection, which is causing it to report a minor sensor error.
Your boiler is struggling to read the temperature from the solar heating connection, which is causing it to report an inaccurate or impossible reading.
Your boiler is looking for an outdoor weather sensor that it cannot find or that has stopped communicating with the system.
Your boiler has lost communication with one of its internal safety sensors, causing it to shut down as a precaution to prevent unsafe operation.
Your boiler's internal computer has lost its connection to one of the sensors or control components, meaning it cannot safely regulate your heating and hot water.
Your boiler is having a conflict between its hot water and heating systems, causing it to pause operations to prevent a system error.
Your boiler's computer is struggling to identify the specific model or setup it is installed in, causing it to stop functioning correctly.
Your boiler's internal computer is struggling to communicate with its internal components, meaning it cannot safely start up.
Your boiler's smart communication system is struggling to get power, which is preventing it from talking to your heating controls properly.
Your boiler is displaying a background system code related to its internal settings that usually does not stop it from working.
Your boiler has detected that the water pressure in your heating system is too low to operate safely and has shut down to protect itself.
Your boiler has lost communication with an internal component, meaning it cannot operate safely and has shut itself down.
Your boiler has lost its identity settings, meaning the control board doesn't know which specific model it is supposed to be operating.
Your boiler has stopped working because it cannot detect the temperature of the water returning from your radiators.
Your boiler has detected a technical fault with the sensor that monitors water returning from your radiators, causing the system to stop working for safety.
Your boiler is struggling to monitor the temperature of your hot water because a sensor has lost its connection.
Your boiler has detected a fault with the sensor that monitors hot water temperature, meaning it cannot safely tell how hot the water is.
Your boiler has detected a problem with the sensor that monitors exhaust gases, meaning it cannot safely measure the temperature of the air leaving the unit.
Your boiler has detected that its exhaust gases are too hot or that a internal heat sensor has failed, causing the system to shut down for safety.
Your boiler is struggling to keep its flame lit and has locked itself out after failing five times in a single day.
Your boiler has detected that the water coming back from your radiators is hotter than the water going out, which usually means there is a circulation problem or a sensor fault.
Your boiler has detected that water is not moving around the system properly, which has caused it to shut down to prevent overheating.
Your boiler has sensed that the exhaust gases are becoming too hot and has shut down as a safety precaution to prevent internal damage.
Your boiler has detected a critical internal fault that has caused it to shut down completely for safety reasons.
Your boiler has detected that a vital safety component has become disconnected, which has caused it to shut down automatically to keep your home safe.
Your boiler has detected that the water pressure inside the system is too low and has failed to top itself up automatically after several minutes of trying.
Your boiler is struggling to communicate with an add-on accessory, such as a room thermostat or a weather compensation sensor.
Your boiler has stopped working because the internal control board and the gas valve have lost the ability to talk to each other.
Your boiler's internal computer is struggling to talk to its internal parts, meaning it has safely shut down to prevent incorrect operation.
Your boiler has detected an internal issue with the part that controls the flow of gas, which means it has safely shut down to prevent any unsafe operation.
Your boiler has detected a technical fault with the internal sensor that monitors the temperature of the water leaving the unit, preventing it from heating up safely.
Your boiler has stopped working because it can no longer communicate with the internal sensor that monitors the temperature of the water leaving the unit.
Your boiler has shut down because it thinks the water inside has become far too hot or a temperature sensor has malfunctioned.
Your boiler has shut down because its internal sensors have detected that the water inside has become dangerously hot.
Your boiler tried to start four times but could not light the flame, which means your heating and hot water will not work until it is reset or repaired.
Your boiler has detected a flame when there shouldn't be one, so it has shut down for safety purposes.
Your boiler's fan, which clears exhaust gases, is either stuck or spinning at the wrong speed, causing the system to shut down for safety.
Your boiler has detected an internal electrical problem with the component that controls the gas flow, causing the system to shut down for safety.
Your boiler has stopped working because it cannot detect a high enough water temperature or it has lost its connection to one of the internal sensors.
Your boiler has stopped working because its internal computer has lost contact with the gas control unit, meaning it cannot safely ignite.
Your boiler has lost its connection to the remote thermostat or controller, which prevents it from knowing when to turn the heating on.
Your boiler has stopped working because it cannot correctly detect the water pressure inside the system.
Your boiler has stopped working because the internal control board and the gas valve are struggling to talk to each other properly.
Your boiler is heating water too quickly or the heat isn't moving around your system fast enough, causing it to shut down to prevent overheating.
Your boiler has paused because the water inside it is heating up much faster than it can be circulated around your home.
Your boiler has shut down because it has detected that the water inside has become far too hot, likely due to a circulation problem.
Your boiler has detected that water is not moving through the system properly, which is often caused by low water pressure.
Your boiler is heating up too quickly when producing hot water, causing it to shut down to prevent damage.
Your boiler has detected an issue with its heat recovery system, which is preventing it from functioning normally and providing heating or hot water.
Your boiler is currently restarting itself and you simply need to wait a moment for the system to finish its startup sequence.
Your boiler is stuck in a setup mode and needs its specific identity codes entered to function properly.
Your boiler's computer memory hasn't been programmed with the specific settings it needs to operate safely and effectively.
Your boiler's main control computer is unable to access its internal memory settings, preventing the unit from starting up.
Your boiler’s internal control board is confused because it has been programmed with the wrong settings for this specific model.
Your boiler has detected that the water pressure is too low, which prevents it from heating your radiators and water properly.
Your boiler has detected very low temperatures and is automatically running its frost protection mode to prevent the internal pipes from freezing.
Your boiler has completely shut down because it cannot run its frost protection cycle, leaving the system at risk of freezing and damage.
Your boiler is struggling to stay lit and has temporarily stopped heating to keep your home safe.
Your boiler has lost its internal settings and the main control board can no longer identify the safety devices it needs to operate safely.
Your boiler has temporarily lost its flame while running, causing it to shut down as a safety precaution.
Your boiler is not receiving enough electrical power from your home's supply to operate safely.
Not faults — these are normal operating states. Tap to expand.
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BoilerFaultCodes