BoilerFaultCodesThe 6 most common faults
Your boiler has detected that the water inside is getting too hot and has shut down to prevent damage.
Why it happens: This fault occurs when water cannot flow through the boiler quickly enough to carry heat away, causing the internal temperature to reach a dangerous level. The most common reasons are a failed pump that isn't pushing water around or a physical blockage, such as air or sludge, trapped within the main heat exchanger.
Check that at least two of your radiator valves (TRVs) are turned to the highest settingEnsure your boiler pressure is between 1.0 and 1.5 bar on the displayTurn the boiler off and back on again at the mains to reset the system
Your boiler is trying to ignite but cannot establish a flame, meaning you have no heating or hot water.
Why it happens: This fault occurs when the boiler's control system attempts to start a flame but fails to detect one within a safe timeframe. The most common reasons include a lack of gas supply to the unit, a worn-out ignition spark plug, or a component failure that prevents the gas valve from opening correctly.
Check if other gas appliances, like a hob, are working to ensure gas is reaching the property.Verify that your gas emergency control valve is in the 'on' position.If you have a pre-payment meter, check that you have sufficient credit.Press the reset button once to see if the boiler restarts.
Your boiler is unable to safely breathe because the pipes that bring in fresh air or take away exhaust fumes are blocked or restricted.
Why it happens: This fault occurs when the boiler's internal sensors detect that air cannot flow freely through the system to support safe combustion. It is usually caused by an external obstruction in the flue pipe, a buildup of debris, or a mechanical failure in the fan that pushes the exhaust gases out of your home.
Check the external flue pipe on the outside of your property for obstructions like bird nests, leaves, or debris.Ensure there are no items like garden furniture or storage boxes blocking the flue terminal.If it is snowing, gently clear any snow or ice buildup from the end of the pipe.
Your boiler has stopped working because an internal temperature sensor is reporting an error and needs to be checked.
Why it happens: This fault occurs when the boiler's main internal temperature sensor fails to send a consistent electrical signal back to the central control board. The most common reason is that the sensor has suffered a physical failure or the wiring connecting it has become loose or damaged over time. Because the boiler can no longer accurately monitor how hot the water is, it shuts down as a safety precaution to prevent overheating.
Full guide for F000Your boiler has sensed that the exhaust gases are getting too hot and has shut down to prevent internal damage.
Why it happens: This fault occurs when the internal sensors detect that the waste gases leaving your boiler have reached an unsafely high temperature. The most common reasons are a significant build-up of limescale or debris inside the heat exchanger, or a lack of water flow preventing the heat from being transferred away from the unit effectively.
Full guide for F003Your boiler started to heat up but the flame went out unexpectedly, causing the system to stop working for safety.
Why it happens: This fault occurs when the boiler's control system successfully lights the burner but then loses the signal that a flame is present, leading to an immediate shutdown. The most common reasons include a buildup of carbon on the detection probe, a blockage in the drainage system that causes water to back up into the heat exchanger, or an incorrect mixture of gas and air.
Full guide for F005on the Intergas Xtreme 24
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 Intergas 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