BoilerFaultCodesThe 6 most common faults
Your boiler is failing to light the flame, which is likely due to a lack of gas reaching the unit or a problem with the ignition system.
Check if other gas appliances, such as a hob, are working to confirm your gas supply is active.Verify that your gas meter has credit if you use a pre-payment meter.Check that the gas isolation valve under the boiler is in the 'on' or 'open' position (usually parallel to the pipe).Press the reset button on the boiler control panel.
Your boiler is failing to light the gas or cannot tell that the flame has successfully ignited, meaning it won't be able to provide heating or hot water.
Check if your home gas supply is active by testing another gas appliance like a hob.Inspect the condensate pipe (plastic pipe leadings outdoors) to ensure it isn't frozen or blocked.Try to reset the boiler by turning the main dial to the reset position for five seconds and then back to the heater symbol.
Your boiler has got too hot and has shut itself down as a safety precaution to prevent damage.
Turn the boiler off and allow it to cool down for 20 minutes.Check that your radiator valves are open and not turned to the off position.Check the boiler pressure gauge and top it up to 1.5 bar if it is too low.Press the reset button on the control panel to restart the unit.
Your boiler has shut down because a temperature sensor has detected that the water inside is getting too hot, likely due to a circulation problem.
Check that all radiator valves are fully open to allow water to flow.Check that the boiler pressure is between 1.0 and 1.5 bar on the gauge.Reset the boiler using the power switch to see if the fault clears.
Your boiler has stopped working because it cannot properly clear away exhaust fumes or draw in fresh air to burn gas safely.
Full guide for 02Your boiler's internal temperature sensor has stopped sending the correct signal, meaning the system doesn't know how hot the water is and has shut down for safety.
Full guide for 06on the Saunier Duval Isomax F30E
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