BoilerFaultCodesThe 6 most common faults
Your boiler has detected that water is not circulating correctly through the system, preventing it from firing up to heat your home or water.
Why it happens: This fault occurs when the boiler's internal sensors do not detect enough water movement to operate safely, usually because the pump has failed or the flow switch is stuck. The most common reason is that the rubber diaphragm inside the flow valve has perished or the pump has become seized after a period of inactivity.
Check that the central heating valves under the boiler are fully openEnsure all radiator valves are turned on and not stuckCheck the boiler pressure gauge and top it up to 1.5 bar if it is too low
Your boiler is lighting but cannot detect that the flame has been lit, causing it to shut down shortly after for safety.
Why it happens: This fault occurs when the boiler's internal sensors fail to confirm that a flame is present, even if you can see it lighting briefly. The most common reason is a worn-out sensing probe that has become covered in carbon soot or a faulty control board that is no longer 'listening' for the flame signal. For safety, the boiler shuts down immediately because it thinks it is leaking unburnt gas.
Check that your gas supply is turned on and other gas appliances are workingRotate the selector switch to the 'Reset' position for five seconds and then back to the heating/hot water iconEnsure the system pressure is between 1 and 1.5 bar on the pressure gauge
Your boiler has detected a system error or internal failure that is preventing it from starting up correctly.
Why it happens: This fault occurs when the boiler's internal computer, the Printed Circuit Board, suffers an electrical failure or loses communication with its sensors and switches. The most common reason is age-related wear to the board's components or loose connections in the wiring that prevent the boiler from performing its safety checks.
Turn the selector switch to the 'Reset' position and hold for at least 5 secondsReturn the switch to the heating or hot water positionCheck that your gas pre-payment meter (if applicable) has credit
Your boiler has detected a general ignition or flame failure, meaning it has temporarily stopped working for safety.
Why it happens: This fault occurs when the boiler tries to light but fails to detect a steady flame after several attempts. The most common reasons are a worn-out ignition electrode that can no longer create a spark, or a faulty gas valve that isn't allowing fuel into the burner.
Turn the main selector dial to the 'Reset' positionHold it for at least 5 seconds, then turn it back to the 'On' or 'Heat' positionCheck if your gas supply is active by testing another gas appliance like a hob
Your boiler has become too hot and has shut itself down as a safety precaution to prevent damage.
Why it happens: This fault occurs when the water inside the boiler exceeds a safe temperature, triggering a safety switch to cut power to the burner. The most common reasons are a failed pump that isn't moving water around the system or a blockage in the main heat exchanger caused by a buildup of sludge and debris. It can also happen if the system has become air-locked, preventing the heat from being carried away from the appliance.
Check that all radiator valves are fully openEnsure the system water pressure is between 1.0 and 1.5 barTurn the selector switch to the reset position for five seconds and then back to the heating/hot water mode
Your boiler has detected a problem safely moving waste gases out through the flue pipe, which has caused it to shut down for safety.
Why it happens: This fault occurs when the boiler's internal safety sensor cannot detect the flow of air needed to clear away fumes. The most common reasons are a cooling fan that has become stuck or dirty, a blockage in the flue pipe outside, or small internal tubes becoming perishd or clogged with debris.
Full guide for 40° neon flashingon the Potterton Performa 28i
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 Potterton 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