BoilerFaultCodesThe 6 most common faults
Your boiler has stopped working because the water pressure inside the heating system has dropped too low.
Locate the filling loop, which is a silver braided hose or a small lever located underneath the boiler.Slowly open the valves on the filling loop to allow water to enter the system while watching the pressure gauge on the front of the boiler.Wait for the needle to reach the green zone, typically between 1.0 and 1.5 bar, then firmly close the valves.
Your boiler has stopped heating because it is struggling to move water through the system, often because the water pressure is too low or the system is blocked.
Check your boiler pressure gauge; if it is below 1 bar, use the filling loop to top it up to 1.5 bar.Ensure all radiator valves are fully open to allow water to flow freely.Restart the boiler using the reset button once the pressure is correct.
Your boiler is experiencing an internal error that has caused it to stop working, but it may simply need a manual nudge to restart properly.
Locate the 'Reset' button on the front control panel.Press and hold the button for 3-5 seconds.Wait up to 60 seconds for the boiler to attempt a restart and see if the code clears.
Your boiler has encountered a general internal communication error and needs to be restarted to attempt to clear the fault.
Locate the Reset button on your boiler's control panelPress and hold the Reset button for 3 to 5 secondsWait 5 minutes to see if the boiler restarts and the error disappears
Your boiler has stopped working because it is not receiving a reliable supply of gas to create a flame.
Full guide for A01Your boiler has failed to light the flame after trying three times, so it has safely shut down to prevent wasting gas.
Full guide for A02on the Ariston Micro Condens
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