BoilerFaultCodesThe 6 most common faults
01
A01 High Engineer
Your boiler has failed to start because it cannot detect a flame, which is likely due to the gas supply being interrupted or a problem with the ignition system.
Full guide for A0102
A21 High Engineer
Your boiler is failing to register that it has cleared its internal air safely, meaning it is preventing itself from igniting for your protection.
Full guide for A2103
A22 High Engineer
Your boiler is failing to detect that the internal flue fan is starting up, which prevents the unit from firing up to provide heating or hot water.
Full guide for A2204
A33 High Engineer
Your boiler's internal mechanism for clearing waste gases is not working correctly, which forces the boiler to shut down for your safety.
Full guide for A3305
A02 High Engineer
Your boiler has failed to light the flame after trying three times, meaning it cannot produce any heat or hot water.
Full guide for A0206
A03 High Engineer
Your boiler has detected that it has become dangerously overheated and has shut itself down to prevent damage.
Full guide for A03on the Ariston Ecogenus 24 RFFI System
Ignition electrodeGas valvePCBIonisation probeAir pressure switchFlue fan
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 Ariston 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