BoilerFaultCodesThe 6 most common faults
Your boiler has stopped working because the water pressure inside the system is currently too low to operate safely.
Locate the filling loop (a flexible silver hose) underneath the boiler.Open the valves on the filling loop to allow cold mains water into the system.Watch the pressure gauge on the front of the boiler until the needle reaches the green zone (typically 1.0 to 1.5 bar).Close both valves firmly and ensure the filling loop is disconnected if it is a temporary hose.
Your boiler has stopped working because the water pressure inside the heating system has dropped too low to operate safely.
Locate the filling loop, which is usually a flexible silver braided hose with one or two valves located underneath the boiler.Gradually open the valve(s) to allow 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 and restart the boiler to clear the fault.
Your boiler has lost power or has an electrical fault, meaning it cannot start up to provide heating or hot water.
Check if other appliances in the house have powerCheck your main consumer unit (fuse box) to see if a circuit has trippedEnsure the boiler's fused spur switch (usually near the boiler) is turned on
Your boiler has lost its ability to measure its own internal temperature correctly, so it has safely shut down to prevent overheating.
Full guide for 06Your boiler is failing to light the flame needed to produce heat and hot water, likely due to a combustion issue.
Full guide for 01Your boiler has stopped working because one of its internal temperature sensors is providing faulty information, preventing it from safely monitoring the water temperature.
Full guide for Red led flashingon the Saunier Duval Semia Condens F30 E
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