13 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
Replaced by: Greenstar 25i
This boiler uses indicator light combinations
Note which lights are on, off, or flashing and at what speed. Match the combination to the cards below. Do not reset until you have noted the pattern. 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 |
|---|---|---|
| 47-311-49 | 25 Si RSF | 2000–2001 |
Tap any card for details
Your boiler has detected a failure in its internal safety systems which is preventing it from starting up correctly to supply heat and hot water.
Your boiler has detected a safety-related issue with its internal heat sensors or water flow, causing it to shut down to prevent damage.
Your boiler has experienced a sudden technical error and has locked itself to prevent damage, requiring a manual reset to attempt to clear the fault.
Your boiler has detected an internal error and has automatically paused its operation to prevent damage, requiring you to manually restart it.
Your boiler has automatically turned itself off because the water inside it has become hotter than the appliance can safely manage.
Your boiler has automatically turned itself off because the hot water inside it has become dangerously hot.
Your boiler has detected an issue with how it clears exhaust fumes, causing it to stop running for safety.
Your boiler's temperature sensor has failed or has a wiring issue, which means the system cannot safely monitor how hot the water is or provide heating and hot water.
Your boiler is struggling to ignite because the internal gas system isn't communicating correctly, meaning you currently do not have heating or hot water.
Your boiler is failing to light the flame, which means it has safely shut itself down to prevent a gas leak.
Your boiler has failed to light the flame several times and has shut down completely to prevent gas from escaping.
Your boiler has reached an unsafe temperature and has automatically shut down to prevent damage and ensure your safety.
Your boiler has detected that the water inside is dangerously overheating and is running the pump constantly to try and cool it down.
Not faults — these are normal operating states. Tap to expand.
BoilerFaultCodes