BoilerFaultCodesThe 6 most common faults
Your boiler has shut down because the water pressure inside the system has dropped too low.
Locate the filling loop valves underneath your boiler.Open the valves gently to allow water into the system until the pressure gauge reads between 1.0 and 1.5 bar.Close the valves firmly and press the reset button on your boiler.
Your boiler has shut down because the water inside isn't flowing properly to carry away the heat.
Check the boiler pressure gauge to ensure it is between 1 and 1.5 bar.Top up the system pressure using the filling loop if it is too low.Bleed your radiators to remove any trapped air, then recheck the pressure.
Your boiler has detected that the water level inside the heating system is too low to operate safely.
Locate the filling loop, which is usually a silver braided hose under the boiler connected to two valves.Slowly open the valves to allow mains water into your heating system.Watch the pressure gauge on the front of the boiler until it reaches the green zone, typically between 1.0 and 1.5 bar.Close both valves tightly and restart the boiler.
Your boiler is trying to start up, but it cannot detect that the flame has successfully lit.
Full guide for E04Your boiler has failed to light because it cannot detect a flame after several attempts, meaning you currently have no heating or hot water.
Full guide for A03Your boiler has detected that it is getting too hot and has automatically shut itself down to prevent internal damage.
Full guide for A 01on the Ariston Egis 24 MFFI
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