9 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
The fault code is already on your display
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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 |
|---|---|---|
| 41-394-14 | istor HE325 | 2003–2011 |
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Your boiler has detected an issue with the flame during operation, causing it to shut down for safety reasons.
Your boiler is failing to start because the electrical supply wires are connected in the wrong order.
Your boiler has stopped working because it has detected a specific internal problem, which it will show by alternating the 'F' with another number or letter.
Your boiler's internal computer is experiencing a communication fault and cannot control the system correctly.
Your boiler has detected that it is getting dangerously hot and has shut itself down to prevent damage.
Your boiler has detected that it is running much hotter than it should be and has shut itself down to prevent any internal damage.
Your boiler has detected that it is running much hotter than it should be and has switched itself off to prevent internal damage.
Your boiler has switched itself off for safety and is displaying a 'lockout' status, which will be accompanied by a second flashing code to tell you exactly what is wrong.
Your boiler has detected that it is becoming dangerously hot and has shut itself down to prevent any internal damage.
BoilerFaultCodes