Ideal is one of the most widely installed boiler brands in the UK. This page collects our guides and the common Ideal combi boiler fault codes, with what each one means and what you can safely check yourself.
Ideal combi boiler error codes
- C0 Central heating signal problem
- F1 Low water pressure
- F2 Flame loss
- F3 Fan fault
- F4 Flow thermistor (temperature sensor) fault
- F5 Return thermistor (temperature sensor) fault
- F6 Outside temperature sensor fault
- F7 Mains voltage too low
- F9 Control board (PCB) not configured
- FD No water flow — air lock, low water or circulation problem
- L1 Low water flow, or flow temperature out of range
- L2 Ignition lockout
- L4 Flow thermistor (temperature sensor) fault
- L6 False flame detected
- L9 Overheating — temperature reading too high
Should you repair or replace?
As a rough rule, if your boiler is more than 10–12 years old and the repair is over a few hundred pounds, it's worth getting a replacement price before you commit. Parts for older models also get harder to find.
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