19 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 |
|---|---|---|
| 47-077-28 | 624 Combi | 2017–present |
| 47-077-33 | 624 COMBI LPG 24 | 2018–present |
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Your boiler has stopped working because it cannot properly control the flow of gas needed to stay alight.
Your boiler has lost its connection to the fuel supply control, meaning it cannot light the flame to provide heating or hot water.
Your boiler's internal temperature sensor for the heating system has developed a fault, meaning the unit cannot safely monitor how hot the water is getting.
Your boiler has detected a problem with the temperature sensor that monitors 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's main control board has lost connection with the display or sensors, meaning it cannot send or receive the signals needed to operate.
Your boiler is struggling to move water around the system properly before it starts the heating process, often due to an air lock or a pump issue.
Your boiler has switched itself off because internal sensors have detected that the water inside is getting too hot.
Your boiler has stopped working because the water pressure inside the system has dropped too low to operate safely.
Your boiler has stopped working because water is not moving around the system properly, which is causing the unit to overheat.
Your boiler has lost its flame while it was running, which means it has stopped providing heating and hot water for safety reasons.
Your boiler has shut down because the sensor detected that the exhaust gases are getting too hot, which is a safety feature to prevent damage or dangerous fumes.
Your boiler has failed to light because it either isn't receiving gas or cannot detect the flame it has created.
Your boiler has failed to ignite or has lost its flame because it isn't receiving the gas it needs to stay lit.
Your boiler has lost its connection to the gas supply due to an internal electronic fault and cannot light the flame.
Your boiler has detected that the internal fan, which safely clears exhaust fumes, is not spinning at the correct speed or has lost power.
Your boiler is currently running a programmed safety cycle to remove air bubbles from the system, which is a normal process and will stop automatically in about 7 minutes.
Your boiler is struggling to accurately measure the temperature of your hot water, which usually means your taps will only run cold.
Your boiler thinks a flame is present when there shouldn't be one, which stops the system from starting up safely.
Not faults — these are normal operating states. Tap to expand.
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BoilerFaultCodes