12 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 |
|---|---|---|
| 41-311-62 | Greenstar R 28 HE System | 2003–2006 |
Appliance names and production years are taken from the UK Product Characteristics Database (the SAP/SEDBUK register). Where a GC number is also printed in this model's own manufacturer manual, both sources were checked to agree.
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Your boiler has lost its internal connection between the main control board and the display panel, meaning it cannot communicate with itself properly.
Your boiler's main control board has lost communication with an internal plug-in module or sensor, meaning it cannot currently operate.
Your boiler's computer memory chip is loose or missing, meaning the system doesn't know which model it is and has stopped working for safety.
Your boiler has stopped working because the internal fan, which clears exhaust gases, isn't spinning fast enough to operate safely.
Your boiler has lost the signal from an external control, such as your room thermostat or programmer, preventing it from firing up.
Your boiler has detected a faulty internal temperature sensor, which means it cannot accurately monitor the water temperature and has shut down as a safety precaution.
Your boiler has shut down because it has detected that the water inside is Getting too hot, which is a safety feature to prevent damage.
Your boiler is failing to light the gas or isn't detecting that the flame has started, causing the system to shut down for safety.
Your boiler's internal computer has encountered a critical electronic software or hardware error that is preventing it from running safely.
Your boiler thinks it can see a flame inside the system even though it should be turned off, which is a safety conflict that prevents it from starting up.
Your boiler is still detecting a flame even though it has tried to shut off the gas, which is a safety conflict causing the system to lock out.
Your boiler has been put into a temporary reset mode because the button was held down too long or pressed accidentally.
BoilerFaultCodes