BoilerFaultCodes
The most common Sime faults
Your boiler has stopped working because the water level inside the system is too low and needs to be topped up.
Locate the silver braided filling loop hoses underneath or near your boilerSlowly open both small valves on the filling loop until you hear water flowingWatch the pressure gauge and close both valves firmly once the needle reaches between 1.0 and 1.2 bar
Your boiler has too much water pressure in the system, which causes it to shut down for safety.
Locate a radiator bleed valve and use a key to release water into a cloth or container.Monitor the boiler's pressure gauge until it drops down into the green zone, ideally 1.2 bar.Ensure the filling loop valves are fully closed so no more water enters the system.Turn the boiler off and back on to reset the fault code.
Your boiler has failed to light the flame, which means you will have no heating or hot water until the issue is resolved.
Check if other gas appliances in your home, like a hob, are working to confirm your gas supply is active.Verify that your gas meter has credit if you use a prepay meter.Press the 'Reset' button on the boiler control panel to see if the lockout clears.
Your boiler has overheated, causing a safety sensor to automatically shut the system down to prevent damage.
Wait for the boiler to cool down completelyCheck that all radiator valves are open and not blockedPress the 'Reset' button on the boiler control panelCheck the system pressure gauge is between 1.0 and 1.5 bar
Your boiler is struggling to detect a flame, meaning it cannot stay alight and providing you with no heating or hot water.
Check that your gas emergency control valve is in the 'on' positionIf you have a prepayment meter, check that you have sufficient creditTry resetting the boiler by turning the selector switch to the reset position for a few seconds
Your boiler has stopped working because water is not moving through the system properly, which is preventing it from heating up safely.
Check that your system pressure is between 1 and 1.5 bar on the pressure gaugeEnsure all radiator valves and isolation valves under the boiler are fully openTry bleeding your radiators to remove any trapped air pockets
Your boiler has detected that the water drain for condensation is blocked or full, causing the system to shut down for safety.
Check the plastic pipe leading from the boiler to the outside drain for signs of freezing or blockages.If the external pipe is frozen, gently pour warm (not boiling) water over it to melt the ice.Inspect the internal condensate trap/siphon for any visible debris if safely accessible from the bottom of the unit.
Your boiler has been manually reset too many times in a short period and has temporarily locked itself for safety reasons.
Wait exactly 60 minutes without pressing any buttons to allow the lockout timer to expire.Ensure the gas supply is turned on and the system pressure is between 1 and 1.5 bar.Attempt one final reset; if the boiler fails to fire, do not attempt further resets and call a professional.
Avoid the next call-out bill
Monthly cover means no unexpected bills when your boiler breaks down.
Affiliate links. We may earn a commission at no extra cost to you.