BoilerFaultCodesThe 6 most common faults
01
30 High DIY-safe
Your boiler has detected an issue with the electrical power supply to the unit while it was running.
What to try first
Check if other appliances in your home have power.Ensure the boiler's fused spur switch is fully turned on.Reset the boiler by following the instructions on the display panel.
02
1 High Engineer
Your boiler has detected an electrical wiring short circuit, causing it to safely shut down to prevent further damage.
Full guide for 103
2 High Engineer
Your boiler is trying to start up, but it cannot detect a flame to keep the burner lit, so it has safely shut down to stop unburnt gas from building up.
Full guide for 204
4 High Engineer
Your boiler's main electronic control unit has encountered an internal communication error and has safely stopped working.
Full guide for 405
5 High Engineer
Your boiler has temporarily stopped working because it cannot safely detect the correct airflow needed for combustion.
Full guide for 506
00 High Engineer
Your boiler's main control computer has encountered an internal error and can no longer safely manage the heating system.
Full guide for 00on the Ideal Systemiser
Printed Circuit Board (PCB)Wiring HarnessFused SpurMain PCBInternal FuseIgnition lead
Based on parts cited in our fault code database. Your engineer will confirm what's actually needed after diagnosis.
Call a Gas Safe engineer if…
- You can smell gas or see signs of a leak
- The Ideal shows an Emergency or High severity code
- The boiler keeps locking out after repeated resets
- You've tried the DIY checks and the fault hasn't cleared
- There's visible water leaking from the boiler
- The flame is yellow or orange instead of blue