80 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 |
|---|---|---|
| 47-406-77 | Greenstar 28CDi Compact ErP | 2015–present |
| 47-406-78 | Greenstar 28CDi Compact ErP LPG | 2015–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's main control unit has encountered a communication error and is unable to operate safely.
Your boiler has temporarily paused to protect itself because it has been running almost continuously without a break for the past 24 hours.
Your boiler is shutting down because it is heating up much faster than it can circulate the water, which often points to a blockage or a pump issue.
Your boiler's computer has lost its internal memory settings regarding safe operating pressure and needs to be reset by a professional.
Your boiler has detected that an internal valve responsible for controlling gas flow is not sealing properly, meaning it cannot operate safely.
Your boiler has detected an internal issue where a component responsible for controlling the fuel supply is failing to shut properly, preventing the system from operating safely.
Your boiler is failing to detect or trigger the heating process required to provide you with hot water.
Your boiler is struggling to circulate water, likely because the internal pump is jammed or there is air trapped inside the system.
Your boiler has detected that water is not circulating properly because the internal pump is either jammed or has air trapped inside it.
Your boiler has detected an issue with the sensor that monitors exhaust gases, so it has safely shut down to prevent incorrect operation.
Your boiler is currently unable to accurately measure the temperature of the water it is heating, so it has stopped providing hot water to keep your system safe.
Your boiler's internal control system has lost its digital connection, meaning it cannot properly send or receive instructions to run your heating or hot water.
Your boiler's computer has detected a serious internal fault that prevents it from operating safely, requiring a qualified professional to inspect or replace the electronic control system.
Your boiler's internal air blower is struggling to run at the correct speed, which is preventing the system from safely igniting your heating and hot water.
Your boiler has detected that air is not flowing through the system correctly, which is preventing it from running safely.
Your boiler is struggling to shut down its internal ventilation system properly, which means it cannot safely restart or regulate itself.
Your boiler has detected airflow when the fan should not have been running, which usually points to a temporary blockage or a sensor reading error.
Your boiler has detected that the internal ventilation fan is spinning faster than it should, which has caused it to shut down for safety reasons.
Your boiler has stopped working because the internal component responsible for pushing air through the system is failing to start.
Your boiler is temporarily locked out because it cannot detect water movement or pressure change when the internal pump starts up.
Your boiler has lost communication with the device that tells it how much water is inside, so it has shut down to prevent damage.
Your boiler has temporarily stopped because the water returning from your radiators is too hot, which helps protect the internal parts from overheating.
Your boiler is temporarily locked out because a part that measures the temperature of the water returning into the system is sending an incorrect reading.
Your boiler has temporarily stopped working because it is unable to accurately read the temperature of the water returning from your radiators.
Your boiler has temporarily stopped because the water returning from your radiators is running hotter than it should be.
Your boiler has lost its connection to an essential safety internal plug, meaning it currently cannot communicate correctly with its control system.
Your boiler has detected that the water inside is heating up unevenly, so it has safely shut down to prevent any damage.
Your boiler has detected that the water inside the unit is getting too hot compared to the water travelling to your radiators, causing it to shut down to prevent damage.
Your boiler has lost its ability to accurately measure the water temperature, so it has safely shut itself down to prevent overheating.
Your boiler has temporarily stopped working because it has detected an electrical fault with the sensor that measures the flow of water inside the system.
Your boiler has temporarily stopped working because it cannot properly read the temperature and flow of the water inside the system.
Your boiler has detected that hot water is flowing in the wrong direction or circulating incorrectly, meaning it cannot heat your home properly.
Your boiler has detected that the water inside the system is getting much hotter than it should be, so it has shut itself down to prevent damage.
Your boiler has sensed that the water inside IT is getting too hot too quickly, causing it to shut down for safety.
Your boiler has temporarily shut down because the internal water temperature has become dangerously high.
Your boiler has detected that it is getting too hot and has automatically switched itself off to prevent any damage or danger.
Your boiler has temporarily stopped working because an internal safety sensor detected that the water temperature inside got too hot.
Your boiler has detected an internal electrical safety fault and has safely locked itself out to prevent any risk.
Your boiler has safely shut down because a critical safety sensor has lost its connection or stopped working properly.
Your boiler has temporarily shut down because the internal temperature has become too high, usually due to a temporary blockage in water flow.
Your boiler has detected that the water inside it is getting much hotter than it should be and has shut down for safety.
Your boiler has detected that the water inside has become dangerously hot and has shut itself down to prevent damage or fire risk.
Your boiler has detected that the water returning to it is dangerously hot and has shut itself down to prevent damage or overheating.
Your boiler has failed to light the flame, which means it has stopped working to keep you safe.
Your boiler has tried to start up, but it cannot detect a flame to keep it burning.
Your boiler has safely shut down because the internal flame went out while it was trying to heat your home or water.
Your boiler has failed to ignite because it cannot properly detect or regulate the gas supply needed to light the flame.
Your boiler has failed to ignite the gas safely and has locked itself out to prevent any risk.
Your boiler has detected that the exhaust gases are getting too hot, too quickly, so it has turned itself off to prevent internal damage.
Your boiler has detected that hot gases are building up inside the system while the water meant to be heating your home is staying cold, so it has safely shut down to prevent overheating.
Your boiler has temporarily stopped because the hot water inside the system has become much hotter than it should be.
Your boiler has detected that the water inside isn't warming up as expected after it fires up, so it has stopped trying to prevent potential damage.
Your boiler has detected that it cannot move water through your radiators or pipes fast enough, causing the internal temperature to rise dangerously high.
Your boiler's computer system has encountered a general internal communication issue that is preventing it from operating correctly.
Your boiler's internal computer has encountered a software glitch or a communication error that is preventing it from starting safely.
Your boiler has suffered an internal control system error and has safely shut itself down to prevent any further issues.
Your boiler has detected an internal computer glitch and has safely shut down to prevent any further issues.
Your boiler has detected an internal computer glitch and has safely shut down to prevent any further issues.
Your boiler's computer is experiencing a critical internal glitch that is preventing it from operating safely.
Your boiler's computer is experiencing a internal communication error that is preventing it from starting up correctly.
Your boiler has detected an internal software or communication error that is preventing it from operating correctly.
Your boiler's computer has encountered an internal communication error and has safely shut itself down to prevent potential damage.
Your boiler's computer has encountered an internal communication error and has shut down to prevent incorrect operation.
Your boiler's computer is experiencing an internal processing error, meaning it has stopped working safely to prevent potential damage.
Your boiler has temporarily stopped working because it cannot properly read one of its internal temperature sensors.
Your boiler's computer has encountered an internal technical glitch that is preventing it from operating correctly.
Your boiler has temporarily locked itself out after trying to fire up too many times in a short space of time.
Your boiler has detected an internal computer error that is preventing it from starting up correctly.
Your boiler is repeatedly trying to start up and shutting down again too quickly without staying on.
Your boiler has detected a flame signal when it shouldn't be running, which is a safety concern that requires immediate professional attention.
Your boiler has detected an issue with the flame and has safely shut down because it cannot ignite or stay lit properly.
Your boiler has detected an internal computer error and has temporarily stopped working for safety reasons.
Your boiler has detected that a flame is still burning inside, even though it has sent a signal to turn the gas off, which indicates a serious safety monitoring fault.
Your boiler is temporarily locked out because it detects a flame when it shouldn't, which is usually a safety precaution triggered by moisture, condensation, or a sensor glitch.
Your boiler has safely shut down because it detected a potential issue with the internal gas valve sealing properly.
Your boiler has detected a potential internal gas leak and has shut down as a safety precaution.
Your boiler is showing this code simply because the reset button was held down for too long or pressed by mistake, which has confused the internal software.
Your boiler has detected an issue with the incoming electricity supply or its internal power connection.
Your boiler has detected that the water pump is not running as expected, which prevents heat from circulating through your home.
Your boiler is currently unable to start up because a small protective electrical fuse inside the unit has blown, cutting power to internal systems.
Not faults — these are normal operating states. Tap to expand.
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BoilerFaultCodes