18 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 |
|---|---|---|
| 47-310-21 | iC28 | 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 has lost communication with the weather sensor outside your home and is now running on its default safety settings.
Your boiler is struggling to detect the flow of water through its system, which means it cannot safely heat your home or provide hot water.
Your boiler is struggling to accurately read the temperature of the water returning to it, which prevents it from heating your home reliably.
Your boiler is having trouble detecting the temperature of the water coming from your taps, which means it cannot heat your hot water properly.
Your boiler's electronic control system has lost its internal connection, meaning the main brain can no longer talk to the other components to request heating or hot water.
Your boiler has detected that the water pressure inside your heating system is either too low or too high, so it has safely shut down to prevent damage.
Your boiler has automatically started a special air-clearing cycle because the water pressure recently dropped too low.
Your boiler has detected that it is getting dangerously hot and has shut itself down to prevent damage.
Your boiler has switched itself off because it has become too hot internally, likely due to a lack of water flow or a blockage.
Your boiler has temporarily stopped working because the water pressure inside the system has risen above the safe limit.
Your boiler has lost some water pressure, so it is working less efficiently to prevent internal damage until you add more water to the system.
Your boiler has detected that a critical safety connection inside its control panel has come loose or is missing, which prevents it from operating correctly.
Your boiler has stopped working because the fan responsible for moving air and removing exhaust gases inside the unit failed to start.
Your boiler has failed to light the flame after several attempts and has switched itself off for safety.
Your boiler's internal fan, which is responsible for safely venting fumes, is failing to spin at the correct speed, causing the system to stop working for safety reasons.
Your boiler has detected an abnormal temperature difference between the water leaving it and the water returning, which usually indicates a circulation problem inside the system.
This is not an error code, but merely a notification confirming that the boiler's manual testing mode has finished successfully.
This code is not an error; it simply confirms that your boiler has finished its setup or testing mode and is returning to normal operation.
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BoilerFaultCodes