22 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
Replaced by: Duo-tec 2 Combi
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Note it down before pressing reset — resetting clears the code immediately. 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 |
|---|---|---|
| 47-075-56 | Duo-tec 2 Combi 33 GA | 2011–2015 |
| 47-075-57 | Duo-tec 2 Combi 40 GA | 2011–2015 |
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Your boiler has lost its connection to the component that controls the fuel supply, meaning it cannot ignite to provide heating or hot water.
Your boiler has detected a communication problem with the part that controls the gas supply, meaning it cannot light safely for heating or hot water.
Your boiler has lost signal from the sensor that monitors the temperature of the water used to heat your radiators.
Your boiler has detected a problem with the sensor that monitors the temperature of the exhaust gases, causing the system to shut down for safety.
Your boiler has detected a problem with the sensor that monitors the temperature of the water returning from your radiators.
Your boiler has switched itself off because it has detected that the water inside has become far too hot.
Your boiler has detected that water is not moving through the system properly, which is causing it to overheat and shut down for safety.
Your boiler has shut down because it detected that the exhaust gases are getting too hot, which is a safety feature to prevent damage.
Your boiler has tried to light several times but has failed, which means the flame is either not starting or not staying on.
Your boiler has lost its connection to the gas supply or cannot detect gas flow, meaning it cannot ignite to provide heating or hot water.
Your boiler has detected a problem with the fan that safely pushes waste gases out of your home, causing the system to shut down for safety.
Your boiler is struggling to provide hot water because the temperature sensor responsible for tracking it has developed a fault.
Your boiler has lost the ability to accurately measure the water temperature for your central heating, so it has shut down to prevent overheating.
Your boiler has detected an issue with the sensor that monitors the temperature of the gases leaving your flue, meaning it has shut down as a precaution to ensure it is operating safely.
Your boiler is struggling to accurately detect the temperature of the water it is heating, so it has shut down to prevent the system from overheating.
Your boiler has detected that it is overheating and has automatically switched itself off to prevent any damage or safety hazards.
Your boiler has stopped working because the water pressure inside the heating system has dropped too low.
Your boiler is struggling to pump water around your heating system effectively, so it has shut down to prevent damage from overheating.
Your boiler has detected that the flue gases are getting too hot, so it has safely shut itself down to prevent any damage.
Your boiler is failing to ignite because it is not receiving enough gas or cannot detect a flame.
Your boiler has detected that the fan, which is essential for safely venting exhaust gases, is not operating correctly and has shut itself down to keep you safe.
Your boiler is struggling to get the water moving around the system properly before it attempts to light the burner.
Not faults — these are normal operating states. Tap to expand.
BoilerFaultCodes