BoilerFaultCodesThe 6 most common faults
Your boiler has shut down because its internal temperature got too hot, likely due to a circulation problem or a blockage.
Why it happens: This fault occurs when the water inside the boiler reaches an unsafe temperature, causing the system to shut down to prevent damage. The most common reason is that water isn't moving through the unit quickly enough, often due to a pump failure, a build-up of sludge, or air trapped in the heat exchanger.
Check that your main gas valve is fully open and you have credit on your meter.Verify that all radiator valves are open and that there is enough water pressure on the boiler gauge (target 1.5 bar).Press the Reset button for two seconds to see if the boiler restarts.
Your boiler has shut down because the water inside has become far too hot, which is often caused by a blockage or a pump that isn't moving water around the system properly.
Why it happens: This fault occurs when the water inside the boiler reaches an unsafe temperature because it isn't moving away from the heat source quickly enough. The most common reasons are a failed pump that can no longer circulate the water or a blockage in the system pipes, often caused by a buildup of sludge or debris. In some cases, a faulty sensor may simply be misreading the temperature even if the water is flowing correctly.
Check that all radiator valves are fully open to allow water to circulate.Check that your system pressure is between 1.0 and 1.5 bar on the gauge.Restart the boiler by pressing the 'Reset' button for two seconds.
Your boiler is failing to light the gas burner properly and has locked itself out for safety after several unsuccessful tries.
Why it happens: This fault occurs when the boiler tries to light the gas burner five times but fails to detect a stable flame. The most common reasons are a build-up of carbon on the ignition probes, a lack of gas supply to the unit, or a internal electrical component failing to generate the necessary spark.
Check if other gas appliances like your hob are working to ensure gas is reaching the propertyEnsure your gas pre-pay meter, if you have one, has creditPress the 'Reset' button on the boiler control panel for two seconds
Your boiler was working but the flame has unexpectedly gone out, meaning the system has stopped providing heat for your safety.
Why it happens: This fault occurs when your boiler successfully starts but then loses its flame while it is running. The most common reasons are a build-up of carbon on the sensing probe or a blockage in the drainage system that causes water to back up into the burner. In some cases, the gas valve may be failing to maintain a steady flow of fuel to keep the flame lit.
Check if other gas appliances in your home, like a gas hob, are working to ensure gas supply is active.Verify that your prepaid gas meter (if applicable) has sufficient credit.Press the 'Reset' button on the boiler control panel for two seconds.
Your boiler has stopped working because the water pressure inside the system has dropped too low to operate safely.
Why it happens: This fault occurs when there isn't enough water circulating through your heating system to allow the boiler to fire up safely. The most common reason is a slow leak from a radiator valve or joint, though pressure can also drop if you have recently bled your radiators and haven't topped the system back up.
Locate the filling loop (a flexible silver hose) underneath or near 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 1.5 bar.
Your boiler is struggling to ignite or detect a flame, causing the system to stop as a safety precaution.
Why it happens: This fault occurs when the boiler tries to light but fails to establish or sense a stable flame within the set time limit. The most common reasons include a lack of gas reaching the burner, worn-out ignition components that can no longer create a spark, or a dirty sensor that cannot tell the boiler the flame is safely lit.
Check that your gas meter is turned on and other gas appliances like the hob are working.If you have a prepaid gas meter, verify that you have sufficient credit.Press and hold the 'Reset' button for two seconds and wait up to three minutes for the venting cycle to complete.
on the Remeha Avanta Plus 35c
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 Remeha 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