BoilerFaultCodesIdeal Optimum 001 Fault codes & diagnostics
0 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
Combi Natural Gas 24 kW 2005 onwards Discontinued
GC Numbers 41-421-7041-421-7141-421-7241-421-96
Replaced by: Isar HE
Download the Ideal Optimum 001 manual
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Versions & GC numbers
The fault code is already on your display
Note it down before pressing reset — resetting clears the code immediately. How to read fault codes →
Which version do you have?
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 |
|---|---|---|
| 41-421-70 | HE 9 | 2005–present |
| 41-421-71 | HE 12 | 2005–present |
| 41-421-72 | HE 15 | 2005–present |
| 41-421-96 | HE 18 | 2005–present |
Status & diagnostic codes 4 operating states & engineer diagnostics
Not faults — these are normal operating states. Tap to expand.
4 operating states & engineer diagnostics
Not faults — these are normal operating states. Tap to expand.
I3 Status Your boiler is operating normally and is currently receiving power from your home's mains electricity supply. Neon I3 Status Your boiler is receiving power from the mains electricity and is operating normally. Neon SG1 Status Your boiler is currently trying to light the flame and this light will turn off normally once the burner is firing correctly. SG1 Status Your boiler is currently trying to light its flame; this light is normal operation and should disappear once the boiler is running successfully.