65 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 |
|---|---|---|
| 47-077-74 | 424 COMBI 2.1 | 2024–present |
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 has detected a thermostat or control unit that is not compatible with this specific Baxi model.
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 can no longer communicate with, which might cause your heating to behave unpredictably.
Your boiler has stopped working because the water pressure inside your heating system has dropped too low to function safely.
Your boiler has detected an internal communication error between its internal parts, meaning it has safely shut itself down to prevent potential damage.
Your boiler has lost communication with one of its internal control components, meaning it cannot operate safely and has shut itself down.
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 is having a communication breakdown with its internal control system, which means it cannot receive instructions to heat your home or water.
Your boiler's internal computer has lost its identification data or is not communicating correctly with its main control board.
Your boiler has encountered a technical data error that prevents it from saving further custom settings, but it should otherwise remain operational.
Your boiler has lost its connection to the sensor that monitors water returning from your radiators, causing the system to stop working as a safety precaution.
Your boiler has detected a fault with the sensor that measures the temperature of the water returning to the unit, causing it to stop running as a safety precaution.
Your boiler is unable to read the temperature of your hot water cylinder, which means you may not have reliable hot water.
Your boiler has detected a fault with the sensor that monitors your hot water temperature, meaning it cannot safely heat your water to the correct level.
Your boiler has temporarily stopped working because it cannot properly read the temperature of the gases leaving the flue.
Your boiler has shut down because a safety sensor has detected that the exhaust gases are becoming too hot or the sensor itself has failed.
Your boiler has temporarily stopped working because it has repeatedly lost its flame over the last 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 glitch.
Your boiler has detected that water is not moving through the system properly, which has caused it to shut down to prevent overheating.
Your boiler has sensed that the exhaust gases are getting too hot and has shut itself down as a safety precaution.
Your boiler has detected a critical internal fault that has caused it to shut down completely for safety reasons.
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 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 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 fault with the internal sensor that monitors the temperature of the water leaving the unit, meaning it cannot safely regulate heat.
Your boiler has lost communication with the internal thermometer that monitors water leaving the unit, causing the system to shut down for safety.
Your boiler has shut down because it thinks the water inside is getting too hot or a temperature sensor has malfunctioned.
Your boiler has shut down because the water inside has become far too hot, likely due to a circulation problem.
Your boiler has tried and failed to light its burner four times, meaning it cannot provide heating or hot water until the issue is resolved.
Your boiler is trying to start up and light the gas, but it cannot detect a steady flame so it safely shuts itself down.
Your boiler has stopped working because the fan that removes exhaust gases is either stuck or spinning at the wrong speed.
Your boiler has detected an internal electrical problem with the component that controls the gas supply, meaning it cannot safely light itself to provide heat or hot water.
Your boiler has detected that the water temperature is too low or a internal sensor has stopped communicating, causing the system to shut down for safety.
Your boiler has temporarily stopped working because the internal computer parts are having trouble talking 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 an internal electrical communication error with the gas valve, meaning it cannot safely ignite to provide heating or hot water.
Your boiler is temporarily locked out because the built-in sensor that measures water pressure is not responding properly.
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 the internal control board and the gas supply valve are temporarily failing to talk to each other.
Your boiler has temporarily stopped because the water leaving the boiler is getting much hotter than the water returning from your radiators.
Your boiler is temporarily pausing because the water inside is heating up much faster than normal.
Your boiler has temporarily stopped working because the water inside it has become too hot.
Your boiler has detected that water is not moving through the system properly, often because the water pressure is too low.
Your boiler is temporarily pausing because the water inside is heating up much faster than expected while you are running the hot tap.
Your boiler is currently restarting itself or finishing a reset cycle and should return to normal operation shortly.
Your boiler is waiting for its control settings to be programmed, which usually happens during a new installation or if the main computer board has been replaced.
Your boiler’s internal computer has lost its specific identity settings and needs to be told exactly which model it is before it can operate.
Your boiler's main control board is having trouble reading its own saved internal settings, which is preventing the system from starting up.
Your boiler’s internal control board is confused because its software does not match the hardware installed, often following a repair or a power glitch.
Your boiler has temporarily stopped working because the water pressure inside the heating system has dropped too low.
Your boiler has temporarily paused because it detected very cold temperatures and is running a built-in frost protection mode.
Your boiler has completely shut down for safety reasons and will not provide heating or hot water.
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's main control board is unable to communicate with its internal safety chip, meaning the boiler has disabled itself for protection.
Your boiler's burner has unexpectedly gone out while running, causing the system to restart or stop to ensure safety.
Your boiler is not receiving enough electrical power from your home's mains supply to operate safely.
Your boiler has temporarily shut down because the electrical voltage supplying it has dropped too low.
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BoilerFaultCodes