10 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
Replaced by: Micron System
This boiler uses LED flash patterns
Count the flashes in one repeating group before the pause. That number is your fault code. Do not reset until you have noted it. 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 |
|---|---|---|
| 41-047-17 | Micron 40FF | 1999–2002 |
Tap any card for details
Your boiler’s internal control board has developed a critical electronic fault and can no longer manage the heating process safely.
Your boiler has entered a safety lockout mode because it failed to light or stay on properly after multiple attempts.
Your boiler has detected an internal electrical or computer error and has stopped working for safety.
Your boiler has switched itself off because it has reached an unsafe temperature and needs to be cooled down and reset.
Your boiler has failed to light after several attempts and has locked itself out for safety.
Your boiler has shut down because it has detected it is getting too hot, usually caused by a blockage or a pump failure.
Your boiler is failing to light or stay lit, meaning it cannot heat your home or water.
Your boiler has switched itself off because it got too hot, likely triggered by a safety sensor to prevent damage.
Your boiler has become too hot and has automatically shut down to protect itself, usually because the water inside isn't circulating properly.
Your boiler has switched itself off because it has reached an unsafe temperature, usually caused by a circulation issue or a temporary blockage.
Not faults — these are normal operating states. Tap to expand.
BoilerFaultCodes