Ideal boiler
fault codes.
What the most common Ideal boiler fault codes mean, what you can safely check yourself, and when you need a Gas Safe engineer. Ideal codes show as a flashing letter and a number.
Before you start
- Never remove the boiler casing – only a Gas Safe engineer should work inside it
- Only reset the boiler as shown in your manual, and not more than once or twice
- If the same code keeps coming back, book a repair
Smell gas? Leave the property and call the National Gas Emergency Service on 0800 111 999.
The quick checks
- Pressure: the gauge should read between 1 and 1.5 bar when the boiler is cold
- Gas: do your hob and other gas appliances work? Is there credit on a prepayment meter?
- Condensate pipe: in freezing weather, is the outside plastic pipe frozen? Only thaw it at ground level, with warm (not boiling) water
- Power: is the boiler’s fused spur switched on?
Common Ideal fault codes
F1 – Low water pressure.
Top up to between 1 and 1.5 bar, as shown in your user guide. If it keeps dropping, there may be a leak – book a repair.
F2 or L2 – Flame loss, or the boiler could not light (ignition lockout).
Check your other gas appliances work, that the gas is on at the meter, any prepayment credit, and that the yellow gas valve under the boiler is open. A gurgling noise while it tries to light can mean a blocked or frozen condensate pipe. Then reset. If it happens again, book a repair.
L1 – The water is overheating or not flowing.
Check the radiator valves are open and the pressure is 1 to 1.5 bar, then reset. If it returns, book a repair.
L3 – No water flow.
Check the pressure, bleed the radiators with the boiler off, check the pressure again, then reset. If it returns, book a repair.
L5 – Too many resets in a short time.
Switch the boiler off at the power and back on. If the original fault returns, book a repair rather than resetting again.
L6 – A false flame was detected.
Reset once. If it returns, it needs an engineer.
F3 – Fan fault.
Reset once. If it returns, it needs an engineer.
F4, F5, F0 – A temperature sensor (thermistor) fault.
Reset once. If it returns, the sensor or its wiring needs an engineer.
F6 – Outside sensor fault (where an outside sensor is fitted).
Reset once. If it returns, it needs an engineer.
F7 – The mains voltage is too low.
Ideal advises having the property’s electrics checked by an electrician.
C0, C2 – A fault with the boiler’s control chip.
Reset once. If it returns, it needs an engineer.
Need a repair?
A diagnostic visit is £92.50 for the first 45 minutes. Once the fault is found, we give you a fixed price for the repair before any work goes ahead – often from photos or a short video of the boiler and its display.
Boiler keeps breaking down?
If your boiler is old and the faults keep coming back, a replacement may cost less than you think. See fixed, fully installed prices with our online boiler price.
About this list
Codes and meanings vary between Ideal models, so check your boiler’s user guide. This guide is based on Ideal Heating’s published fault code information and its Logic user guides. Ideal’s own guide is at idealheating.com.