BoilerFaultCodesThe 6 most common faults
Your boiler is struggling to move water through your heating system, usually because there isn't enough water inside or the internal pump is blocked.
Check your boiler's pressure gauge to ensure it is between 1 and 1.5 barIf the pressure is low, use the external filling loop to top it up to 1.5 barEnsure all radiator valves are fully open to allow water to circulate freely
Your boiler is struggling to push water around your heating system, usually because there is air trapped inside or the water pressure is too low.
Check your boiler pressure gauge to ensure it is between 1 and 1.5 barIf the pressure is low, use the filling loop to top it up to the correct levelBleed all the radiators in your home to release trapped air, then re-check the pressure
Your boiler has detected that hot water is not flowing around your radiators effectively, likely due to low pressure or a blockage.
Check your boiler's pressure gauge and ensure it is between 1 and 1.5 barIf the pressure is low, use the filling loop to top it upCheck that all radiator valves throughout the house are fully open
Your boiler has detected that it is running too hot and has automatically shut itself down to prevent damage to its internal parts.
Full guide for 1 01Your boiler is currently unable to detect the water pressure inside the system, which is preventing it from firing up safely.
Full guide for 1 02Your boiler has detected that water is not moving through your heating system correctly, which is preventing it from heating your home safely.
Full guide for 1 03on the Ariston Clas System 28
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