Ideal boilers show a letter and a number, such as F1 or L2. Some codes mean different things on different Ideal models, so each page tells you which model the meaning applies to. If in doubt, check your user guide.
F1 (low pressure) and L2 (ignition lockout) mean the same on every Ideal guide we checked, and they are the codes Ideal owners search for most. For L2, Ideal's advice is to check the condensate pipe and your gas supply before calling anyone.
| Code | What it means | Models | Can you fix it? |
|---|---|---|---|
| F1 | Low water pressure. | Logic Combi (ESP1), Exclusive 2 | Usually yes |
| L2 | Ignition lockout: the boiler failed to light. | Logic Combi (ESP1), Exclusive 2 | Checks first |
| L1 | No water flow or overheat, or a condensate pipe blockage, depending on the model. | Logic Combi (ESP1), Exclusive 2 | Checks first |
| F2 | Flame loss on Ideal Logic boilers (overheat or no water flow on the Exclusive 2). | Logic Combi (ESP1), Exclusive 2 | Checks first |
| L5 | Return thermistor fault (Logic) or too many resets (Exclusive 2). | Logic Combi (ESP1), Exclusive 2 | Checks first |
| F3 | Fan fault (Ideal Logic). | Logic Combi (ESP1) | Checks first |
| F4 | Flow thermistor fault (Ideal Logic). | Logic Combi (ESP1) | Checks first |
| C0 | BCC activation fault. | Ideal boilers (Ideal's general fault code guide) | No, engineer only |
| C2 | BCC chip fault. | Ideal boilers (Ideal's general fault code guide) | No, engineer only |
| F0 | No water flow thermistor. | Ideal boilers (Ideal's general fault code guide) | No, engineer only |
| F5 | Return thermistor fault. | Logic Combi (ESP1) | No, engineer only |
| F6 | Outside sensor fault. | Logic Combi (ESP1) | No, engineer only |
| F7 | Low mains voltage. | Ideal boilers (Ideal's general fault code guide) | No, engineer only |
| FA | Flow and return pipes are reversed. | Ideal boilers (Ideal's boiler faults FAQ) | No, engineer only |
| Fn | Flame loss. | Logic Combi (ESP1) | No, engineer only |
| L3 | No water flow. | Ideal boilers (Ideal's general fault code guide) | Checks first |
| L4 | Varies by model: flow thermistor fault (Logic Combi (ESP1)); flame loss (Exclusive 2). | Logic Combi (ESP1), Exclusive 2 | No, engineer only |
| L6 | Varies by model: false flame lockout (Logic Combi (ESP1)); fan fault (Exclusive 2). | Logic Combi (ESP1), Exclusive 2 | No, engineer only |
| Ln | Flame loss. | Logic Combi (ESP1) | No, engineer only |