BoilerFaultCodesThe 6 most common faults
Your boiler has shut down because it has detected it is getting too hot or that water is not moving through the system properly.
Check that your system pressure is between 1 and 1.5 barEnsure all radiator valves and the boiler isolation valves are fully openPress the reset button once the boiler has had time to cool down
Your boiler has failed to light because it cannot detect a flame, causing the system to lock itself for safety.
Check if your gas supply is active (e.g., check other gas appliances or prepay meter credit)If it is winter, check that your external condensate pipe hasn't frozenPress the Reset button once to see if the boiler restarts
Your boiler has stopped working because the water pressure in the pipes has become too low for it to operate safely.
Locate the external filling loop, which is usually a silver flexible hose with one or two black lever valves.Open the valves slowly until you hear water moving and watch the pressure gauge needle reach 1.0 to 1.5 bar.Close both valves tightly and restart the boiler to clear the fault.
Your boiler has lost its ability to measure the temperature of the water leaving the unit, meaning it cannot operate safely and has shut itself down.
Full guide for F4Your boiler has detected that the pipes carrying water in and out of the unit have been installed or connected the wrong way around.
Full guide for FAYour boiler's electronic brain is unable to communicate correctly, which has caused the system to shut down for safety reasons.
Full guide for L Eon the Ideal Mexico
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