BoilerFaultCodesThe 6 most common faults
Your boiler has become too hot and has shut itself down for safety purposes.
Why it happens: This fault occurs when the water inside the boiler exceeds a safe temperature limit, triggering an emergency shutdown to prevent damage. It is usually caused by a lack of water flow, often due to a pump failure or a blockage within the pipework that prevents heat from being carried away from the unit. In some cases, a build-up of limescale or sludge acts as an insulator, causing the internal components to get too hot too quickly.
Check that all radiator valves are fully open to allow water to circulate.Ensure your system water pressure is between 1 and 1.5 bar on the gauge.Allow the boiler to cool down and press the reset button on the control panel.
Your boiler has become too hot and has automatically shut itself down to prevent damage and ensure safety.
Why it happens: This fault occurs when the water temperature inside the boiler exceeds a safe limit, causing the safety sensors to cut the power. The most common reasons are a pump failure that stops water from moving or a blockage in the system that prevents heat from being carried away from the boiler.
Check that your radiator valves are openEnsure there is enough water pressure in the system (usually between 1 and 1.5 bar on the gauge)Once the boiler has cooled down, press the reset button on the front control panel
Your boiler has failed to light or maintain a flame, meaning your heating and hot water have stopped working.
Why it happens: This fault occurs when the boiler's control system attempts to start the burner but cannot detect a stable flame. The most common reasons are a lack of gas supply to the unit, a worn-out ignition component that fails to create a spark, or a dirty internal sensor that cannot 'see' the flame once it has lit.
Check if other gas appliances, like a hob, are working to ensure gas is reaching your homeCheck if your gas meter has creditPress the 'Reset' button on the boiler control panel
Your boiler has detected that the water inside is getting too hot and has shut itself down as a safety precaution.
Why it happens: This fault occurs when the water within the boiler's heat exchanger reaches an unsafe temperature, triggering a safety cutout to prevent damage. The most common reason is a lack of water flow, often caused by a failing pump or a blockage in the pipework that prevents heat from being carried away from the unit. It can also be triggered by a faulty internal sensor that is incorrectly reporting the temperature to the control board.
Check that your radiator valves are open and not turned to zero.Verify that the system water pressure is between 1 and 1.5 bar on the gauge.Allow the boiler to cool down for 20 minutes and press the Reset button.
Your boiler’s internal computer has encountered a critical error and cannot communicate properly with the system.
Why it happens: This fault occurs when the boiler's main control board suffers a hardware failure or a corruption in its software, meaning it can no longer process commands. The most common reason is age-related wear to the electrical components on the board, though it can also be triggered by a sudden power surge or moisture getting into the control box.
Full guide for LEYour boiler's internal computer has encountered a critical electronic failure and can no longer control the heating process safely.
Why it happens: This fault occurs when the boiler's main control board suffers an internal electronic failure or loses communication with its sensors. The most common reason is age-related wear on the electrical components or a sudden power surge that has damaged the delicate circuitry. Because the board can no longer safely monitor the flame or water temperature, it shuts the system down as a safety precaution.
Full guide for HEon the Ideal Mexico HE
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