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 |
|---|---|---|
| 47-310-19 | iC24 | 2015–present |
| 47-310-27 | iC Economiser 27 | 2015–present |
| 47-310-29 | iC Economiser 35 | 2015–2018 |
| 47-310-31 | iC Economiser 39 | 2015–2018 |
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Your boiler has lost connection with the sensor that monitors the outdoor temperature, which might cause your heating to respond incorrectly to the weather.
Your boiler has lost its ability to accurately measure the temperature of the water leaving the unit, usually causing it to shut down as a safety precaution.
Your boiler has detected a problem with the sensor that monitors the temperature of the water returning from your radiators, preventing it from heating your home safely.
Your boiler is having trouble detecting the temperature of your hot water, which usually means it cannot heat it up for your taps and showers.
Your boiler's internal computer system has lost connection with its controls, meaning it cannot receive the instructions needed to heat your home.
Your boiler has detected that the water pressure is either too low for the system to run or there is a problem with the sensor that measures it.
Your boiler has lost track of the water pressure inside the system because the internal sensor is sending an incorrect signal or has failed.
Your boiler is simply running a routine automatic cycle to clear air bubbles from the pipes because the power was recently switched off or interrupted.
Your boiler has stopped working because the water pressure is too low and needs to be topped up.
Your boiler has switched itself off because it detected that the internal water temperature has become dangerously hot or a sensor has failed.
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 detected that there is too much water pressure in the system or the pump is forcing water through too quickly.
Your boiler has lost water pressure and has shut itself down to prevent damage to the internal components.
Your boiler has lost its internal electrical connection signal, which is usually caused by low water pressure or a loose wiring link inside the unit.
Your boiler's internal fan is failing to start, which means the system cannot safely clear exhaust fumes and has shut down as a precaution.
Your boiler has tried to light several times but cannot establish a flame, meaning your heating and hot water will not work.
Your boiler has stopped working because the internal fan, which safely clears waste gases, is not spinning at the correct speed.
Your boiler has detected an issue with the temperature difference between its flow and return pipes and has temporarily shut itself down to prevent potential damage.
Not faults — these are normal operating states. Tap to expand.
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BoilerFaultCodes