23 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 |
|---|---|---|
| 47-393-54 | Promax Ultra Combi 24 ErP | 2015–present |
| 47-393-55 | Promax Ultra Combi 28 ErP | 2015–present |
| 47-393-56 | Promax Ultra Combi 33 ErP | 2015–present |
| 47-393-57 | Promax Ultra Combi 40 ErP | 2015–present |
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Your boiler has lost its connection to the gas supply mechanism, meaning it cannot safely ignite to provide heating or hot water.
Your boiler has detected an issue with the internal component that controls the gas supply, meaning it cannot safely ignite to heat your water or home.
Your boiler has lost the ability to accurately measure the temperature of the water circulating to your radiators, causing it to shut down for safety.
Your boiler has detected a communication issue with the sensor that monitors the temperature of the gases leaving your flue, causing it to stop working for your safety.
Your boiler is struggling to accurately measure the temperature of the water returning to it, so it has shut down as a precaution to prevent overheating.
Your boiler is struggling to get water moving through its internal system effectively before it tries to fire up, causing it to shut down for protection.
Your boiler has detected that it is overheating and has automatically switched itself off to prevent damage.
Your boiler has detected that there is too much water pressure inside the system, which can cause it to stop working to prevent internal damage.
Your boiler has stopped working because the water pressure inside the heating system has dropped below the minimum level required to operate safely.
Your boiler is struggling to pump water around your heating system, which means it has stopped working to prevent itself from overheating.
Your boiler has stopped working because it cannot light the internal flame needed to heat your water.
Your boiler has detected that the temperature in the flue pipe is too high, causing it to shut down to prevent overheating.
Your boiler is trying to start but cannot detect a flame, likely because it is not receiving any gas or is having trouble lighting.
Your boiler is attempting to start but cannot detect a gas supply, so it has locked itself for safety reasons.
Your boiler has detected an issue with its internal communication or gas supply system, causing it to stop operating as a safety precaution.
Your boiler's safety checks have detected that the temperature sensors monitoring the water flow are not reading correctly, so the boiler has shut down to prevent damage.
Your boiler has detected that the internal fan responsible for venting exhaust gases safely is not operating correctly, so it has shut down to prevent any unsafe conditions.
Your boiler has detected that water is not flowing through the system correctly, which could lead to it overheating if it keeps running.
Your boiler is currently unable to sense the temperature of your hot water, which means it has stopped heating water to prevent overheating.
Your boiler has detected a flame when it should be turned off, so it has safely shut itself down to prevent a potential hazard.
Your boiler has stopped working because the water pressure inside the system has dropped too low to operate safely.
Your boiler started to heat up but the flame unexpectedly went out, causing the system to stop working for safety.
Your boiler has tried to light several times but cannot establish a flame, meaning you currently have no heating or hot water.
Not faults — these are normal operating states. Tap to expand.
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BoilerFaultCodes