Appliance hub
Ideal Boiler Fault Codes
Browse the available Ideal boiler fault codes in one place, then open the exact code page for the likely meaning, safe first steps, and when to stop troubleshooting.
Browse the parent brand page: Ideal or compare across brands in the global boiler fault-code hub.
Fault codes
18
Issue categories
6
Related guides
3
Most common faults to check first
Common problems in this cluster
sensor problems
Start with F5, then compare 3 related code pages in this cluster.
fan and flue problems
Start with C5, then compare 2 related code pages in this cluster.
ignition problems
Start with F4, then compare 2 related code pages in this cluster.
flame-loss problems
Start with F2, then compare 1 related code pages in this cluster.
low-pressure problems
Start with D4, then compare 1 related code pages in this cluster.
PCB and control problems
Start with C7, then compare 1 related code pages in this cluster.
Common fault categories
sensor (4)
fan and flue (3)
ignition (3)
flame-loss (2)
low-pressure (2)
PCB and control (2)
Most searched / most useful codes
F9 meaning and fix
The boiler is not seeing healthy water circulation
F4 meaning and fix
The boiler has failed to ignite on demand
L2 meaning and fix
The boiler has lost or failed to prove flame
C5 meaning and fix
Fan, flue, or air pressure sensing problem
C6 meaning and fix
Fan, flue, or air pressure sensing problem
C7 meaning and fix
Control board or internal communication fault
F2 meaning and fix
Flame detection has been lost during operation
F3 meaning and fix
Fan, flue, or air pressure sensing problem
HF meaning and fix
The boiler has failed to ignite properly
L1 meaning and fix
The boiler has overheated or hit a high temperature limit
L5 meaning and fix
Control board or internal communication fault
L6 meaning and fix
Flame detection has been lost during operation
All fault codes in this cluster
18 code pages currently available for this brand and appliance cluster.
| Code | Meaning | Issue type | Severity |
|---|---|---|---|
| C0 | A boiler sensor is giving an invalid reading | sensor | medium |
| C2 | A boiler sensor is giving an invalid reading | sensor | medium |
| C5 | Fan, flue, or air pressure sensing problem | fan flue | high |
| C6 | Fan, flue, or air pressure sensing problem | fan flue | high |
| C7 | Control board or internal communication fault | pcb control | high |
| D4 | System water pressure is too low | low pressure | medium |
| F1 | System water pressure is too low | low pressure | medium |
| F2 | Flame detection has been lost during operation | flame loss | high |
| F3 | Fan, flue, or air pressure sensing problem | fan flue | high |
| F4 | The boiler has failed to ignite on demand | ignition | high |
| F5 | A boiler sensor is giving an invalid reading | sensor | medium |
| F6 | A boiler sensor is giving an invalid reading | sensor | medium |
| F9 | The boiler is not seeing healthy water circulation | circulation | high |
| HF | The boiler has failed to ignite properly | ignition | high |
| L1 | The boiler has overheated or hit a high temperature limit | overheat | high |
| L2 | The boiler has lost or failed to prove flame | ignition | high |
| L5 | Control board or internal communication fault | pcb control | high |
| L6 | Flame detection has been lost during operation | flame loss | high |
Useful guides
Boiler Fault Codes: When to Stop and Call a Professional
Boiler issues need a more cautious approach than most white goods, especially where gas, combustion, or repeated lockouts are involved.
When to Call an Appliance Engineer
Guidance on recognising when simple checks have been exhausted and it is time to arrange a repair.
Why Your Boiler Keeps Losing Pressure
Learn the difference between a one-off pressure drop and repeated pressure loss, plus the safe top-up and recheck advice that stays within normal user controls.