28 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 |
|---|---|---|
| 47-349-18 | LOGIC COMBI C24 | 2016–present |
| 47-349-19 | LOGIC COMBI C30 | 2016–present |
| 47-349-75 | LOGIC MAX COMBI C30P | 2018–present |
| 47-348-56 | Logic combi 24 | 2009–2016 |
| 47-348-57 | Logic combi 30 | 2009–2016 |
| 47-348-58 | Logic combi 35 | 2009–2016 |
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Your boiler has lost communication with its internal computer chip, meaning the main control board no longer recognizes the specific model it is supposed to be operating.
Your boiler has detected that the water pressure inside the system is too low to run safely and has stopped working as a result.
Your boiler is failing to stay lit or cannot detect its own flame, meaning it has shut down for safety and will not provide heating or hot water.
Your boiler has started an ignition process but the flame has gone out, meaning the system has shut down for safety.
Your boiler has detected an issue with the internal fan, which is preventing the system from safely clearing exhaust gases and starting the ignition process.
Your boiler has detected an issue with the sensor that monitors the temperature of the water leaving the unit, meaning it cannot safely regulate heat.
Your boiler has stopped working because it is having trouble reading the temperature of the water flowing through it, so it has safely shut down to prevent overheating.
Your boiler has detected an issue with the sensor that monitors the temperature of the water returning to the unit, causing it to stop working for safety.
Your boiler has lost the ability to accurately measure the temperature of the water returning to it, so it has safely shut down to prevent overheating.
Your boiler has lost connection with the sensor that monitors the outdoor temperature, making it difficult for the system to adjust its heat settings efficiently.
Your boiler has detected that the electricity supply coming into your home is at a lower voltage than it needs to operate safely.
Your boiler's computer brain has lost its settings or is experiencing an electrical fault, preventing the system from starting up.
Your boiler's computer memory is blank or incorrect, meaning it doesn't currently know how to operate itself.
Your boiler's main internal computer is failing to communicate correctly with its internal control systems, preventing it from safely starting up.
Your boiler has detected that the water temperature sensors are giving conflicting readings, often caused by the flow and return pipes being switched or a sensor failing.
Your boiler has lit correctly but the flame has gone out unexpectedly, often due to a temporary interruption in the gas supply or a blocked condensate pipe.
Your boiler has detected that the water is heating up too quickly or isn't moving through the system properly, causing it to overheat and shut down for safety.
Your boiler has shut down because the water inside it has become too hot, usually due to a lack of circulation or a blockage in the system.
Your boiler has stopped working because it cannot light a flame, which is often caused by a lack of gas supply or a blocked pipe.
Your boiler has detected a problem with the internal temperature sensor that monitors the water leaving the unit, causing it to shut down as a safety precaution.
Your boiler has stopped working because it can no longer accurately read the temperature of the water inside the unit.
Your boiler has detected a problem with the sensor that monitors the temperature of the water coming back into the unit, causing it to shut down for safety.
Your boiler has lost the ability to read the temperature of the water returning to it, so it has shut down as a precaution to prevent overheating.
Your boiler thinks a flame is present even though it hasn't been safely ignited, causing the system to shut down for safety.
Your boiler's computer brain has lost its settings or is experiencing an electrical fault, preventing the system from starting up.
Your boiler's computer brain has lost its settings or is experiencing an electrical fault, preventing the system from starting up.
Your boiler has tried and failed to start up five times in a short window and has now locked itself out for safety.
Your boiler is struggling to keep its flame lit, which means it cannot heat your water or radiators reliably.
Not faults — these are normal operating states. Tap to expand.
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BoilerFaultCodes