BoilerFaultCodesThe 6 most common faults
Your boiler has detected that the water pressure is too low, which prevents it from heating up or providing hot water.
Locate the silver filling loop cable underneath your boiler.Slowly open the valve(s) to allow water into the system while watching the pressure gauge.Close the valve(s) firmly once the pressure gauge needle reaches between 1.0 and 1.5 bar.
Your boiler has stopped working because it cannot light the gas flame needed to provide heat and hot water.
Check that your gas emergency control valve is in the 'on' positionIf you have a pre-payment meter, check that you have sufficient creditPress the Reset button on the control panel to see if the boiler restarts
Your boiler has likely overheated or has air trapped inside, causing it to shut down for safety.
Locate the reset button on your boiler control panel and press it onceCheck that your radiator valves are open to ensure water can flow properlyBleed your radiators using a radiator key to remove any trapped air from the system
Your boiler has failed to light the gas and has locked itself for safety, which means you currently have no heating or hot water.
Check that your gas stopcock or meter valve is turned onIf you have a prepaid gas meter, ensure you have credit remainingPress and hold the 'Reset' button to see if the boiler restartsCheck if other gas appliances, like a hob, are working to confirm gas supply
Your boiler has detected that water is not circulating properly through the system, causing it to shut down to prevent overheating.
Check that the boiler pressure is between 1.0 and 1.5 bar on the pressure gauge.Ensure all radiator valves and isolation valves under the boiler are fully open.Gently bleed your radiators to remove trapped air that might be blocking water flow.
Your boiler has stopped working because the water pressure inside the heating system has dropped too low to operate safely.
Locate the filling loop (a silver braided hose) underneath the boiler.Open the small valve(s) 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 the valve(s) tightly and ensure the boiler resets.
on the Sime iQE Comfort 30
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