BoilerFaultCodesThe 6 most common faults
01
1 High DIY-safe
Your boiler has detected that the water inside is getting too hot because trapped air is blocking the flow and the circulation pump is not running properly.
What to try first
Check your central heating pressure gauge to ensure it is at the correct level (usually around 1 to 1.5 bar).Bleed your radiators starting from the ground floor up to release any trapped air in the system.Check if the circulation pump is stuck and try resetting it, or consult your manual if the issue persists.
02
2 High Engineer
Your heating system has detected an internal wiring or connection fault, which stops it from working properly to keep you safe.
Full guide for 203
4 High Engineer
Your boiler is trying to start up, but it cannot detect a flame because gas is not getting through properly or the ignition isn't sparking.
Full guide for 404
5 High Engineer
Your boiler is having trouble lighting or staying lit because it cannot detect a steady flame, which is likely due to a blocked drainpipe, low gas supply, or an ignition issue.
Full guide for 505
6 High Engineer
Your boiler is failing to detect a proper flame, so it has safely shut itself down to prevent any gas from building up.
Full guide for 606
8 High Engineer
Your boiler has stopped working because the internal airflow fan is not spinning at the correct speed, which usually means it is blocked or struggling to connect properly.
Full guide for 8on the Daikin EKOMBG 22
Central heating pumpAutomatic air ventCable harnessSwitch S1Switch S2Ignition electrode
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 Daikin 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
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