Error code
Ideal Boiler Fault Code F4
Quick answer
F4
The boiler has failed to ignite properly
First safe action
Check whether other gas appliances appear to have lost supply, without dismantling the boiler.
Meaning
Ideal boiler fault code F4 usually means the boiler could not ignite or complete its startup sequence correctly.
Likely causes
- Temporary gas supply interruption
- Ignition or electrode fault
- Control problem affecting startup
Safe first checks
- Check whether other gas appliances appear to have lost supply, without dismantling the boiler.
- If the manufacturer permits a user reset, try the standard reset process once.
- Stop further reset attempts if the fault returns.
How to reset
- Follow the reset instructions shown on the boiler control panel or in the manual.
- If the code reappears after one reset, book a qualified engineer.
When to call an engineer
If the fault returns after one reset, stop there and arrange a Gas Safe registered engineer.
Safety warning
Do not remove the boiler casing or try to work on gas, ignition, or combustion components yourself.
Useful hub links
Related fault codes
F3 for Ideal Boiler
Fan, flue, or air pressure sensing problem
F5 for Ideal Boiler
A boiler sensor is giving an invalid reading
HF for Ideal Boiler
The boiler has failed to ignite properly
L2 for Ideal Boiler
The boiler has failed to ignite properly
F1 for Ideal Boiler
System water pressure is too low
F2 for Ideal Boiler
Flame detection has been lost during operation
Relevant guides
Frequently asked questions
Can I keep resetting a Ideal boiler with F4?+
No. If F4 returns after one standard user reset, stop there and arrange a qualified engineer if the manual gives no safe next step.
Is F4 something I can repair myself?+
Boiler faults should be treated cautiously. Stay within the user checks in the manual, and leave gas, combustion, and internal boiler repairs to a qualified professional.