BoilerFaultCodesThe 6 most common faults
Your boiler has shut down because the water inside it has become too hot, usually due to a lack of water flow or a circulation problem.
Why it happens: This fault occurs when the water inside the boiler exceeds a safe temperature limit and cannot be cooled down quickly enough. The most common reasons are a pump failure preventing the water from moving or a blockage within the pipework that restricts flow. In some cases, it can also be triggered by a faulty sensor giving a false reading to the boiler's control board.
Check that your boiler pressure is between 1.0 and 1.5 bar on the front gauge.Ensure all radiator valves are fully open and not turned off.Reset the boiler by turning the mode dial to 'reset' for two seconds and then back to your desired setting.
Your boiler has tried to light several times but cannot establish a flame, meaning it has shut down for safety.
Why it happens: This fault occurs when the boiler's control system attempts to start the burner multiple times but fail to detect a stable flame. The most common reasons are a lack of gas supply reaching the unit, a blocked burner, or a faulty component that is unable to generate the spark required to ignite the gas.
Check if other gas appliances, like a hob, are working to ensure gas is reaching the propertyCheck if your gas meter credit has run outIf it is freezing outside, check if the white plastic condensate pipe leading outdoors is frozenPress the Reset button on the front of the boiler
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 the water pressure inside your heating system drops below a safe level, causing the boiler to shut down to prevent internal damage. The most common reasons are a slow leak from a radiator valve or pipework, or air being released from the system through recent bleeding of radiators.
Locate the filling loop (usually a silver flexible hose) underneath the boiler.Slowly open the blue or black taps on the filling loop until you hear water entering.Watch the pressure gauge and close the taps firmly when the needle reaches between 1 and 1.5 bar.
Your boiler has switched itself off because it started to light but the flame went out or could not be detected.
Why it happens: This fault occurs when the boiler's control system loses the signal that a flame is present, causing it to shut down for safety. The most common reasons are a worn-out sensor that can no longer 'see' the flame, or a physical issue like an unstable gas supply or a blocked flue preventing a clean burn.
Check if your other gas appliances (like a hob) are working to ensure gas is reaching the propertyIf you have a prepay meter, check that you have credit and the valve is openIn freezing weather, check if the white plastic condensate pipe outside has frozen and gently thaw it with warm waterReset the boiler by turning the control knob to 'Reset' and then back to your desired setting
Your boiler has failed to maintain a flame, which means it has stopped providing heating and hot water to protect itself.
Why it happens: This fault occurs when the boiler's control board loses the signal that a flame is present, causing the system to shut down for safety. It is typically caused by a blockage in the condensate drainage pipe, a faulty gas valve, or worn-out ignition components that can no longer detect or sustain a steady flame.
Check if other gas appliances in your home, like a gas hob, are working correctly.Verify that your gas prepaid meter (if applicable) has enough credit.Press the Reset button on the boiler control panel to attempt a restart.
Your boiler is struggling to keep its flame lit, which means it cannot heat your water or radiators.
Why it happens: This fault occurs when the boiler's internal computer can no longer detect the flame required to heat the water, causing the system to shut down for safety. The most common reasons are a build-up of carbon on the sensing probes, a blockage in the flue, or an inconsistent supply of gas reaching the burner.
Check if other gas appliances in your home, like a hob, are working to confirm gas supply.If your gas is on a pre-pay meter, ensure you have sufficient credit.Reset the boiler by turning the mode knob to 'RE' and back to the 'On' position.
on the Ideal Logic Combi ESP1
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