BoilerFaultCodesThe 6 most common faults
01
20, 21, 22, 23, 24 High Engineer
Your boiler has temporarily stopped working because it cannot properly read the temperature of the water inside the system.
Full guide for 20, 21, 22, 23, 2402
1 High Engineer
Your boiler has automatically shut down because the internal water temperature has become dangerously high.
Full guide for 103
4 High Engineer
Your boiler has tried to start up, but it cannot detect a flame to keep it burning.
Full guide for 404
5 High Engineer
Your boiler is trying to start up, but it cannot reliably detect the flame needed to keep the burners running safely.
Full guide for 505
6 High Engineer
Your boiler is trying to light up, but it cannot safely detect the flame so it shuts itself off to keep your home safe.
Full guide for 606
8 High Engineer
Your boiler has detected that the internal fan responsible for safely pushing out exhaust gases is not spinning at the correct speed.
Full guide for 8on the Intergas Combi Compact HRE
Temperature sensor (S2)Sensor wiring harnessNTC temperature sensorCentral heating pumpAutomatic bypass valveIgnition 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 Intergas 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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