7 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
Replaced by: Logic Heat
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 |
|---|---|---|
| 41-399-10 | Icos HE30 | 2006–2011 |
| 41-399-16 | Icos HE36 | 2006–2011 |
Tap any card for details
Your boiler has detected that it is running without enough water and has shut itself down to prevent damage to its internal components.
Your boiler has detected an internal error or has become too hot and has safely shut itself down as a precaution.
Your boiler's main computer control panel is experiencing a software or internal communication error and cannot operate the system.
Your boiler has detected that the gases it is producing are significantly hotter than they should be, so it has shut itself down to prevent damage or overheating.
Your boiler has detected that the gases moving through your flue are getting dangerously hot, so it has automatically shut itself down to prevent damage.
Your boiler has stopped working because it failed to light correctly, causing it to lock itself down for safety.
Your boiler has detected that the exhaust gases are becoming dangerously hot and has shut itself down to prevent damage or fire risk.
BoilerFaultCodes