15 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
The fault code is already on your display
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 |
|---|---|---|
| 47-348-74 | Logic Code Combi 26 | 2011–2013 |
| 47-348-75 | Logic Code Combi 33 | 2011–2013 |
| 47-348-76 | Logic Code Combi 38 | 2011–2013 |
Tap any card for details
Your boiler's internal computer has lost its 'identity' or connection to its configuration card, meaning it cannot safely command the heating or hot water to turn on.
Your boiler has detected an internal issue and is prompting you to perform a manual reset to see if it can clear the error and restart successfully.
Your boiler's electronic brain is unable to read its internal configuration card, meaning it cannot operate safely or reliably.
Your boiler thinks it sees a flame when there shouldn't be one, which is a safety feature that has caused the system to shut down.
Your boiler has detected an issue with the electrical fan that clears exhaust gases, preventing it from starting up for safety reasons.
Your boiler has stopped working because the flame has gone out unexpectedly, often due to a temporary interruption in your gas supply or a sensor issue.
Your boiler has become too hot and has shut itself down as a safety precaution to prevent damage.
Your boiler has lost its ability to measure the temperature of the water leaving the unit, which has caused it to stop working for safety.
Your boiler has detected that the water inside it has become dangerously hot and has shut itself down to prevent damage.
Your boiler is not receiving enough electrical power from your home's supply to operate safely and has shut down to protect its internal parts.
Your boiler has stopped working because the water pressure inside the system has dropped too low, which is usually easy to fix by topping it up.
Your boiler is unable to flow water or gas properly and has stopped working to prevent damage.
Your boiler has detected that water isn't moving through the system properly or a temperature sensor has failed, preventing it from heating your home safely.
Your boiler has lost connection to the sensor that measures the temperature outside, which may cause your heating to be less efficient or unresponsive.
Your boiler's internal sensor that monitors the temperature of the water returning to the unit has stopped working correctly, causing the system to shutdown for safety.
BoilerFaultCodes