BoilerFaultCodesThe 6 most common faults
Your heating system is losing water through a leak, causing the pressure to drop too low for the boiler to operate safely.
Why it happens: This fault occurs when water escapes from the sealed pipework, causing the internal pressure to drop below the level needed for the boiler to pump heat around your home. The most common reasons are a slow leak from a radiator valve, a perished seal inside the boiler, or a failing expansion vessel that can no longer regulate system pressure.
Locate the external filling loop (usually a silver braided hose with two small valves).Slowly open both valves to top up the water until the pressure gauge needle matches the red set point.Ensure both valves are tightly closed once the pressure is restored.
Your boiler has stopped working for safety reasons and needs to be reset manually to try and restart the system.
Why it happens: This fault occurs when the boiler has tried to ignite several times but failed to detect a flame, causing the system to shut down for safety. The most common reasons are a lack of gas reaching the burner, a worn-out ignition spark, or the boiler's internal sensor not recognising that the flame has lit.
Locate the reset button on the control panelPress the reset button once and release itWait up to 5 minutes to see if the boiler fires up and the status lights remain steady
Your boiler is failing to light the gas flame and has shut itself down for safety.
Why it happens: This fault occurs when the boiler attempts to start up but cannot confirm that a flame has successfully lit. The most common reasons are a worn-out ignition spark that fails to catch the gas, or a dirty sensor that cannot 'see' the flame even after it has started. It can also be caused by a lack of gas reaching the unit due to a faulty internal valve.
Check that your gas supply is turned on and other gas appliances are workingPress and hold the reset button for several seconds to restart the ignition sequenceCheck outside to ensure the white condensate pipe hasn't frozen in cold weather
Your boiler is receiving power correctly, but it has failed to ignite or stay lit, causing it to shut down for safety.
Why it happens: This fault occurs when the boiler's control system attempts to start the heating process but cannot detect a stable flame. The most common reasons are a worn-out component that creates the spark, a failure in the valve that delivers gas to the burner, or a fault within the main control board that manages the ignition sequence.
Check that your gas supply is turned on at the meterPress the reset button on the front control panelMonitor the boiler to see if it fires up or if the light returns
Your boiler is failing to light because it isn't receiving enough gas to stay running safely.
Why it happens: This fault occurs when the boiler detects that the gas coming into the unit isn't at a high enough pressure to safely maintain a flame. The most common reasons include a blockage in the gas pipes, a faulty regulator outside at your meter, or an internal component like the gas valve failing to open fully. To protect your home, the boiler automatically shuts down because it cannot guarantee a stable and clean burn.
Ensure your gas stopcock is fully open.If you have a prepayment meter, check that you have sufficient credit.Check if other gas appliances, like a cooker, are working to confirm your gas supply is active.
Your boiler is stuck in its starting sequence because it cannot confirm the fan is working correctly to clear away waste gases.
Why it happens: This fault occurs when the boiler's internal computer signals the fan to start, but fails to receive confirmation that air is moving through the system to safely clear waste gases. It is usually caused by a mechanical failure of the fan motor, a blockage in the flue, or a faulty sensor failing to detect the airflow.
Full guide for LED3on the Ideal Mexico Super 40ff - 80ff
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 Ideal 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