BoilerFaultCodesThe 6 most common faults
Your boiler is struggling to move water through the system, usually because there is trapped air, a closed valve, or a blockage preventing proper flow.
Check all radiator valves in your home are fully openCheck your boiler's pressure gauge and top up the system to between 1.0 and 1.5 bar if lowBleed any radiators that feel cold at the top to release trapped air
Your boiler is struggling to move enough water through your heating system, so it has shut down to prevent overheating.
Check that all radiator valves throughout your home are fully open.Verify your heating system pressure gauge is between 1 and 1.5 bar, and top it up using the filling loop if it is too low.Restart the boiler using the reset button.
Your boiler has detected that the water pressure inside the system has dropped too low to operate safely.
Locate the external filling loop, usually found underneath the boilerOpen the filling valve slowly until the pressure gauge on the front panel reads between 1.0 and 1.5 barClose the valve tightly and check the boiler display to see if the fault has cleared
Your boiler has detected that hot water is not flowing around your radiators effectively, causing it to shut down to prevent overheating.
Check that all radiator valves throughout your home are fully open.Ensure your system pressure gauge is reading between 1.0 and 1.5 bar.If pressure is low, use the filling loop to top it up to the correct level.
Your boiler has detected that it is running too hot and has automatically shut itself down to prevent damage to its internal components.
Full guide for 1 01Your boiler is struggling to detect the water pressure inside the system because the sensor that monitors it is faulty or blocked.
Full guide for 1 02on the Ariston Clas HE Evo
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