BoilerFaultCodesThe 6 most common faults
Your boiler has stopped working because the water pressure is too low and needs to be topped up.
Locate the external filling loop (the flexible silver hose usually found underneath the boiler).Slowly open the one or two small valves on the hose until you hear water flowing.Watch the pressure gauge and close the valves tightly once the needle reaches between 1.0 and 1.2 bar.
Your boiler is failing to light properly, which means it will not be able to provide heating or hot water until the issue is resolved.
Check if your gas supply is active by testing another gas appliance like a hobEnsure your gas meter has credit if you use a prepay meterReset the boiler by turning the selector switch to the reset position for a few seconds
Your boiler has likely overheated or has an airlock, causing it to shut down as a safety precaution.
Check that your system pressure is between 1.0 and 1.5 bar on the gauge.Ensure all radiator valves are fully open to allow water to flow.Attempt to reset the boiler by turning the selector dial to the 'R' position for a few seconds.Bleed your radiators to remove any trapped air from the system.
Your boiler has stopped working because the waste water pipe that carries moisture away from the unit is blocked or full.
Check the white plastic pipe exiting the house for ice if the weather is freezing.Thaw any frozen external pipes using a hot water bottle or warm (not boiling) water.If possible, ensure the internal trap or siphon isn't visibly blocked by debris.
Your boiler has been reset too many times in a short period and has temporarily locked itself for one hour as a safety precaution.
Wait for 60 minutes without touching the boiler to allow the internal timer to expire.Ensure your gas supply is active (check other appliances) and that any external valves are open.After the hour has passed, attempt one final reset; if the boiler fails again, do not keep resetting and call a Gas Safe engineer.
Your boiler has tried and failed to light the flame several times in a row, causing it to shut down for safety.
Check that your gas emergency control valve is in the 'on' positionIf you have a prepay meter, check that you have sufficient creditReset the boiler by turning the selector knob to the 'R' position for a few seconds
on the Sime Murelle Pro HE System R
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 Sime 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
Avoid the next call-out bill
Monthly cover means no unexpected bills when your boiler breaks down.
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