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 (usually a silver braided hose with one or two valves underneath the boiler)Slowly open the valve(s) to let mains water enter the systemMonitor the pressure gauge until the needle reaches the green zone between 1.0 and 1.5 bar, then turn the valve(s) firmly off
Your boiler's internal water pressure is currently too high, which means the system is holding more water than it is designed to manage safely.
Locate a radiator in your home with a bleed valve.Place a cloth or small container under the valve.Use a radiator key to slowly release air and then water until the pressure gauge on the front of the boiler drops back to between 1.0 and 1.5 bar.
Your boiler has detected that the amount of water circulating through your heating system is too low, so it has safely stopped working to prevent any damage.
Locate the filling loop, which is usually a small silver braided hose with one or two valves located underneath the boiler.Slowly open the valve(s) to let mains water into the system until the pressure gauge on the front of the boiler reads between 1.0 and 1.5 bar.Close the valve(s) tightly to stop the flow; the boiler should then automatically restart.
Your boiler is failing to light because it is not receiving gas or cannot sense a flame, meaning you currently have no heating or hot water.
Full guide for 01Your boiler has detected that it is running too hot and has automatically shut itself down to prevent damage.
Full guide for 05Your boiler is currently unable to read the temperature of the water used for your radiators, so it has safely shut itself down to prevent overheating.
Full guide for 06on the Saunier Duval Thema F 30 E Plus
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 Saunier Duval 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