BoilerFaultCodesThe 6 most common faults
Your boiler is trying to light but cannot spark or maintain a flame, meaning you have no heating or hot water.
Why it happens: This fault occurs when the boiler's internal computer tries to start the burner multiple times but cannot detect a successful flame. The most common reason is a problem with the gas supply or a worn-out ignition spark, but it can also be triggered by a build-up of debris on the internal sensors that monitor the fire.
Check that your gas emergency control valve is in the 'on' position.Verify if other gas appliances, such as a hob, are working to confirm gas supply.If you have a pre-payment meter, ensure you have sufficient credit.Press the 'Reset' button on the boiler control panel for 2 seconds.
Your boiler has shut down because the water inside it has become too hot, causing it to overheat for safety.
Why it happens: This fault occurs when water cannot circulate 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, a blockage in the pipework, or air trapped within the heat exchanger. It acts as a safety 'trip' to prevent the appliance from being damaged by extreme heat.
Check that all radiator valves are fully open to allow water to flow.Ensure your system pressure is between 1.0 and 1.5 bar on the gauge.Press the 'reset' button on the boiler control panel once the unit has cooled down.
Your boiler has detected that the water pressure is too low for it to run safely, or there is a blockage preventing water from circulating.
Why it happens: This fault occurs when the boiler detects that there isn't enough water pressure in the system to operate safely, or the water isn't moving through the unit correctly. The most common reason is a gradual loss of pressure through small leaks or after bleeding your radiators, but it can also be triggered by a faulty pump that isn't pushing water around the circuit.
Check the pressure gauge on your boiler or under the sink; it should be between 1.0 and 1.5 bar.Locate the filling loop (a flexible silver hose) and slowly open the valves until the pressure reaches 1.2 bar.Ensure all radiator valves are open and your external pump (if applicable) is running.
Your boiler has sensed that the water returning from your radiators is hotter than the water leaving the boiler, which usually means there is a circulation problem or a sensor fault.
Why it happens: This fault occurs when the boiler's internal sensors detect that the system is operating in reverse, with the return pipe being hotter than the flow pipe. The most common reason is a circulation failure, often caused by a faulty pump or a blockage in the heat exchanger that prevents water from moving through the boiler correctly. It can also be triggered if one of the temperature sensors has failed and is providing an incorrect reading to the control board.
Full guide for 24Your boiler has detected an issue with the fan, which means it cannot safely move air and gas through the system to start the heating process.
Why it happens: This fault occurs when the boiler's control system loses communication with the fan or detects that it isn't spinning at the required speed. The most common reasons are a mechanical failure of the fan motor itself, loose internal wiring, or a fault on the main circuit board failing to send power to the unit.
Full guide for 29Your boiler has sensed that the water returning to it is significantly hotter than the water going out, which usually means there is a blockage or a sensor error causing the system to stop for safety.
Why it happens: This fault occurs when the boiler detects that the water coming back from your radiators is much hotter than the water it just sent out, which shouldn't happen during normal operation. The most common reason is a lack of water flow caused by a blockage, trapped air, or a failing pump, but it can also be triggered if the electronic sensors that measure temperature become faulty and provide 'garbage' readings to the control board.
Full guide for 30on the Intergas Combi Compact HRE 36/30
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