BoilerFaultCodesThe 6 most common faults
Your boiler has switched itself off because an external safety device, such as a thermostat or pressure switch, has detected an issue and broken the electrical circuit.
Why it happens: This fault occurs when an external safety component connected to the boiler’s control board detects a potential hazard and breaks the electrical circuit to stop operation. The most common reason is an underfloor heating safety thermostat triggering because the water is too hot, or a gas pressure switch detecting that the incoming fuel supply is unstable.
Check if your room thermostat or programmer is set too low or has run out of batteriesIf you have underfloor heating, check if the floor has overheated and tripped the safety limitReset the boiler by pressing the reset button for two seconds
Your boiler is struggling to ignite or keep the flame burning, and it is now trying to clear itself out before attempting to start again.
Why it happens: This fault occurs when the boiler's control system cannot detect a steady flame after it tries to light. The most common reasons are a worn-out ignition spark, a blocked airway, or a faulty gas valve that isn't letting enough fuel into the burner.
Check if other gas appliances, like a hob, are working to ensure there is a gas supply.If you have a prepaid meter, check that you have enough credit.Press the Reset button once to see if the boiler restarts.
Your boiler has tried to light itself several times but has failed, likely because there is no gas supply or the ignition part is dirty or broken.
Why it happens: This fault occurs when the boiler is unable to detect a flame after several attempts to start up. The most common reason is a lack of gas reaching the burner, often caused by a closed valve, an issue with the gas meter, or a buildup of carbon on the part that creates the spark.
Check if other gas appliances in your home, like a hob, are working to ensure gas is reaching the property.If you have a prepayment meter, check that you have remaining credit and the valve is open.Press the Reset button on the boiler control panel for one to two seconds.
Your boiler has detected that there is not enough water inside the system to operate safely, or the internal pump is struggling to move the water around.
Why it happens: This fault occurs when the internal sensors detect that water isn't moving through the heat exchanger as it should, leading to a risk of overheating. The most common reasons are a pump that has seized or failed, a loss of system pressure, or a physical blockage like an air lock preventing flow.
Check your system pressure gauge; if it is below 1 bar, top up the water using your boiler's filling loop until it reads between 1 and 1.5 bar.Ensure all radiator valves and your isolation valves underneath the boiler are fully open.Turn the boiler off at the fused spur for 30 seconds, then switch it back on to reset the fault.
Your boiler has failed to light the flame needed to produce heat or hot water.
Why it happens: This fault occurs when the boiler's internal sensors detect that the water coming back from your radiators is hotter than the water being sent out, which is physically impossible under normal conditions. The most common reason is that one of the temperature sensors has failed or is sending the wrong information to the control board. It can also happen if the pump is moving water in the wrong direction or if there is a significant blockage in the system's pipework.
Full guide for é2Your boiler has detected an electrical safety issue where the power supply is not properly grounded or the internal control board has failed.
Why it happens: This fault occurs when the boiler's internal computer detects that the electrical supply is missing a secure connection to the ground. The most common reason is a loose or corroded wire within the boiler itself, or a critical failure of the main control board which prevents it from sensing the electricity correctly.
Full guide for e3on the Remeha Avanta 18V
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