BoilerFaultCodesThe 6 most common faults
01
E02 High DIY-safe
Your boiler has stopped working because the water pressure inside the heating system has dropped too low.
What to try first
Locate the filling loop (usually a silver braided hose with one or two valves underneath the boiler).Slowly open the valve(s) to allow mains water into the system while watching the pressure gauge.Stop filling once the needle reaches the green zone, typically between 1.0 and 1.5 bar, then ensure the valves are fully closed.
02
E08 High DIY-safe
Your boiler has detected that the water level inside the heating system is too low to operate safely.
What to try first
Locate the filling loop (a silver braided hose) underneath the boilerOpen the valves on the filling loop to allow cold mains water to enter the system until the pressure gauge reads between 1.0 and 1.5 barClose the valves firmly and check for any visible leaks on your radiators
03
E04 High Engineer
Your boiler is failing to ignite the flame needed to heat your water and radiators, despite a few automatic attempts to start.
Full guide for E0404
A03 High Engineer
Your boiler has tried multiple times to start but failed to produce a flame, so it has safely shut itself down to prevent a gas buildup.
Full guide for A0305
A01 High Engineer
Your boiler has detected that it is getting too hot and has automatically shut itself down to prevent internal damage.
Full guide for A0106
A36 High Engineer
Your boiler has detected that the exhaust gases leaving the unit are dangerously hot, so it has safely shut itself down to prevent damage.
Full guide for A36on the Ariston Bravo 24 MFFI
Pressure relief valvePressure sensorExpansion vesselFilling loopPressure sensor/transducerIgnition electrode
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