BoilerFaultCodesThe 6 most common faults
Your boiler has detected that there is not enough water flowing through the system to keep it running safely.
Locate the filling loop valves beneath your boiler.Open the valves gently to top up the system pressure until the gauge reads between 1.0 and 1.5 bar.Close both valves tightly and press the reset button on your boiler.
Your boiler has stopped working because water is not moving through the system quickly enough to prevent it from getting too hot.
Check that your radiator valves are fully openEnsure your boiler pressure is between 1 and 1.5 barGently bleed your radiators to remove trapped air
Your boiler has shut down because the water pressure inside the system is too low to operate safely.
Locate the filling loop valves underneath your boiler.Open the valves gently to allow water to enter the system until the pressure gauge reads between 1.0 and 1.5 bar.Close both valves firmly and press the reset button on your boiler.
Your boiler has failed to ignite properly and stopped working because it did not detect a flame after several attempts.
Check if your gas supply is working by testing another gas appliance like a hob.Locate the reset button on your Ariston boiler and hold it down for 5 seconds to restart the system.Check your condensate pipe outside to ensure it isn't frozen or blocked, which can prevent the boiler from firing.
Your boiler is struggling to move water through the system properly, which is causing it to stop running to prevent overheating.
Check that the boiler pressure is between 1 and 1.5 bar on the displayEnsure all radiator valves are fully open to allow water to flowCheck for any visible leaks around the pipework or radiators
Your boiler is failing to light the gas even though it is trying to start up.
Check if your gas supply is turned on at the meterCheck if other gas appliances in your home are workingPress the Reset button once to see if the boiler restarts
on the Ariston Clas HE R 12
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