56 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
This boiler uses LED flash patterns
Count the flashes in one repeating group before the pause. That number is your fault code. Do not reset until you have noted it. 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 |
|---|---|---|
| 47-406-77 | Greenstar 28CDi Compact ErP | 2015–present |
| 47-406-78 | Greenstar 28CDi Compact ErP LPG | 2015–present |
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Your boiler is notifying you that it is currently running, but it has detected a minor inconsistency in how it is circulating water around your system.
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 has stopped working because the internal component responsible for clearing exhaust gases is not spinning, preventing the burner from safely igniting.
Your boiler has detected that its internal air fan is spinning much faster than it should be, causing the system to stop working to ensure safety.
Your boiler has detected that it is running too hot and has automatically shut itself down to prevent any damage or safety issues.
Your boiler is trying to start, but it cannot detect a flame, so it has safely shut itself down to prevent gas from building up.
Your boiler has detected a signal that suggests a flame is present when it should not be, leading the system to shut down for safety reasons.
Your boiler has stopped heating because the flame inside went out while it was trying to run.
Your boiler has been told to stop running by an external device, such as a smart thermostat or a frost protection controller.
Your boiler's internal computer is struggling to communicate with its main control unit, which means the system has stopped working to prevent further damage.
Your boiler has detected an issue with the control system that manages the gas supply, so it has safely shut down to prevent any risk.
Your boiler's fan has been running non-stop for the last day, which suggests the system is struggling to vent correctly or has a faulty sensor.
Your boiler's internal computer is experiencing a major communication error and is unable to safely control the system.
Your boiler's main control unit is experiencing a communication error or electrical glitch that is preventing it from operating correctly.
Your boiler's computer system has encountered an internal error and cannot operate correctly.
Your boiler's internal computer is experiencing a communication error and has decided to shut down to prevent potential damage.
Your boiler's main control computer is experiencing a temporary glitch or internal error, which has caused it to pause its normal operation as a safety precaution.
Your boiler's computer system has encountered an internal error and has temporarily shut itself down to prevent any further issues.
Your boiler's computer is struggling to read internal electronic signals, which has caused it to stop working to ensure safety.
Your boiler's computer system has encountered an internal glitch and needs to be restarted or reset by a professional.
Your boiler's computer is experiencing a temporary software confusion which is preventing it from starting up correctly.
Your boiler is struggling to breathe properly, meaning it cannot safely clear exhaust gases and has shut down to protect your home.
Your boiler is currently heating the water faster than your radiators or taps can use it, causing it to throttle down or pause to prevent overheating.
Your boiler is failing to light because it cannot detect a flame, likely due to a gas supply issue, a blocked flue, or a faulty ignition sensor.
Your boiler has detected that the internal fan is running when it should be idle, which indicates a potential issue with the air pressure sensing system.
Your boiler is struggling because the internal water pump is either jammed or has trapped air inside it, preventing water from circulating properly to heat your home.
Your boiler has detected that the flame is still burning even though it has told the gas supply to shut off.
Your boiler's internal computer is failing to communicate correctly with its external controls, preventing your heating or hot water from turning on.
Your boiler has detected an internal software or communication error and has safely shut itself down to prevent potential damage.
Your boiler is heating up much faster than it should, which has caused it to automatically shut down to prevent potential damage from overheating.
Your boiler is heating the water much faster than it is able to move it away, causing the system to stop as a safety precaution to prevent overheating.
Your boiler has lost its ability to accurately measure the temperature of the water flowing through the heating system because one of its internal sensors is sending a faulty electrical signal.
Your boiler has lost its ability to measure the temperature of the water flowing through the system, so it has purposefully stopped working to prevent overheating.
Your boiler has temporarily paused itself because it hasn't had a proper rest period in the last day, and it should clear on its own once it cools down.
Your boiler's computer has lost its internal memory settings regarding safe operating pressure and needs to be reset by a professional.
Your boiler is struggling because the electricity supply it is receiving is weaker than it needs to operate reliably.
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 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 is struggling to read its internal configuration settings, which is preventing it from starting up correctly.
Your boiler is overheating because it cannot move the hot water away from the heating unit quickly enough, or it is struggling to accurately read its own temperature.
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 is struggling to shut down its internal ventilation system properly, which means it cannot safely restart or regulate itself.
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 is struggling to accurately measure the temperature of the water returning to it, which causes it to stop working to protect the system from overheating.
Your boiler is failing to detect a request for heat from your thermostat or internal timer, likely due to a loose wire or a disconnected control link.
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 detected that it is getting too hot and has automatically switched itself off to prevent any damage or danger.
Your boiler has failed to light the flame, which means it has stopped working to keep you safe.
Your boiler's computer system has encountered a general internal communication issue that is preventing it from operating correctly.
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 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's reset button has been held down for too long, causing the system to enter a settings mode that prevents it from firing.
Your boiler has stopped working because it cannot safely ignite or maintain its internal flame.
Not faults — these are normal operating states. Tap to expand.
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BoilerFaultCodes