18 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 |
|---|---|---|
| 47-920-28 | Isomax F28E A | 2001–present |
| 41-920-37 | Envirotek F28E SB | 2003–2003 |
| 47-920-39 | Envirotek F28E | 2003–2003 |
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Your boiler is operating normally and there are no current faults detected.
Your boiler is struggling to clear exhaust gases effectively, so it has safely shut down to prevent any risk of fumes entering your home.
Your boiler is failing to light the internal flame, which means it cannot produce any hot water or heating.
Your boiler has detected that it is getting too hot and has automatically shut itself down to prevent damage.
Your boiler has lost the ability to accurately measure the temperature of the water being sent to your radiators, so it has safely shut down to prevent overheating.
Your boiler is struggling to detect the temperature of the water it is trying to heat for your taps and shower, so it has stopped providing hot water to prevent overheating.
Your boiler is struggling to accurately measure the temperature of the water stored inside it, so it has stopped heating that water to prevent potential issues.
Your boiler is currently unable to accurately read the water pressure in the system, preventing it from operating safely.
Your boiler's air circulation system, which is essential for safely venting gases, has stopped responding correctly, causing the system to shut down for your safety.
Your boiler has detected that the internal pump, which moves hot water around your home, is stuck or blocked and cannot circulate heat.
The control panel on your boiler is unable to communicate with the main system, meaning the boiler has stopped working to prevent incorrect operation.
Your boiler's electronic brains have encountered an internal error and cannot safely operate the system.
Your boiler has detected that it is dangerously overheating and is running its internal pump to try and cool itself down.
Your boiler has detected a problem with the internal mechanism that controls the gas supply, meaning it cannot safely start up or maintain a flame.
Your boiler's internal computer is struggling to talk to its main control unit, meaning the system has shut down as a precaution.
Your boiler has switched itself off because the system water pressure has dropped too low to operate safely.
Your boiler has detected that water is not circulating through the system correctly, which has caused it to stop working for safety.
Your boiler has detected an issue with the main control board's communication or data processing, which has caused it to stop working for your safety.
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BoilerFaultCodes