34 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 |
|---|---|---|
| 47-393-38 | Apollo 25 | 2011–2015 |
| 47-393-37 | Apollo 30 | 2011–2015 |
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Your boiler has shut down because the water inside it has become too hot, too quickly, or is not circulating properly.
Your boiler has stopped heating because it is unable to accurately measure the temperature of the water flowing through it, likely due to a loose wire or a faulty sensor.
Your boiler has detected an external safety device, such as an overheat thermostat or external control, that has cut the power to the system to prevent damage.
Your boiler has detected that it is getting dangerously hot and has shut itself down to prevent damage or fire risk.
Your boiler has stopped because it cannot maintain a steady flame, meaning it will currently provide no heating or hot water.
Your boiler is failing to light the flame properly, which means it has automatically shut down to prevent gas from building up in the system.
Your boiler has lost the ability for its internal electronic parts to talk to each other correctly, meaning it will likely stop heating your home to stay safe.
Your boiler has stopped working because the internal fan mechanism, which clears waste gases safely, is not starting or running as it should.
Your boiler's computer memory has encountered a digital error and cannot correctly interpret its own settings, causing it to stop operating securely.
Your boiler has detected a communication error within its internal computer, meaning it cannot safely operate and has shut down as a precaution.
Your boiler has detected an internal electronic error within its main control system, causing it to shut down for safety reasons.
Your boiler's internal computer is struggling to communicate with its parts, meaning it cannot safely command the heating or hot water to turn on.
Your boiler has stopped working because it cannot properly clear away the combustion gases, so it has safely shut itself down to prevent any risk.
Your boiler has detected an internal electrical connection failure, which is preventing it from starting up reliably.
Your boiler has detected that it is getting too hot and has automatically switched itself off to prevent any damage or safety issues.
Your boiler has detected that the electrical supply wires have been connected the wrong way round.
Your boiler has detected an issue with the fuel supply system, meaning it cannot ignite safely to provide heating or hot water.
Your boiler has lost the ability to accurately measure the temperature of the water circulating through your radiators, so it has shut down to prevent overheating.
Your boiler has detected a communication error with its exhaust sensor, causing it to shut down for safety reasons.
Your boiler is struggling to accurately read the temperature of the water returning to it, which prevents the system from heating your home properly.
Your boiler has detected that it has become dangerously hot and has automatically shut itself down to prevent damage or fire risk.
Your boiler has detected that water is not moving effectively around your heating system, which forces the boiler to shut down to prevent overheating.
Your boiler has detected that the flue gases are becoming too hot, causing the system to shut down for safety reasons.
Your boiler has stopped working because it cannot light the internal flame, which is likely due to the gas supply being cut off or the ignition failing to spark.
Your boiler has stopped working because it is failing to receive a consistent supply of gas or is struggling to ignite properly.
Your boiler has stopped working because it cannot detect that the internal fan, which is essential for safely exhausting gases, is running correctly.
Your boiler has stopped heating your home or water because it is failing to read the internal temperature correctly.
Your boiler has detected that the internal control board is not the correct version required for your specific model, preventing it from functioning safely.
Your boiler has lost the ability to accurately measure the temperature of the hot water inside it, so it has shut down to prevent overheating.
Your boiler has detected that it is overheating and has shut itself down to prevent internal damage.
Your boiler has stopped working because the water pressure inside the system has dropped too low to operate safely.
Your boiler has detected that water is not flowing around your heating system correctly, which prevents it from safely producing heat.
Your boiler has stopped working because it cannot detect a flame or is not receiving the gas supply needed to stay lit.
Your boiler has detected that the internal fan responsible for safely removing exhaust gases is not working correctly, so it has shut down to keep your home safe.
BoilerFaultCodes