BoilerFaultCodesThe 6 most common faults
Your boiler has shut itself down for safety because it failed to light or detected an internal problem.
Why it happens: This fault occurs when the boiler has tried to ignite several times but failed to establish a stable flame. The most common reason is a lack of fuel reaching the burner, often due to a faulty gas valve or worn-out ignition sparks that can no longer light the gas safely.
Locate the reset button on the front control panel.Press and hold the reset button for several seconds.Check if your gas supply is active by testing another gas appliance like a hob.
Your boiler has detected that the water leaving the unit is getting too hot too quickly, causing it to shut down to prevent damage.
Why it happens: This fault occurs when the water inside the boiler heats up much faster than the system can carry it away, often due to a blockage or a pump failure. It is essentially a safety mechanism that trips when the unit detects that the heat isn't being circulated properly into your radiators or hot water tank. Common culprits include a seized internal pump or a buildup of debris that has restricted the flow of water through the main heat exchanger.
Check that all radiator valves are fully open to allow water to circulate.Ensure the central heating bypass valve (if visible) is not closed.Check that the system pressure gauge is between 1 and 1.5 bar.
Your boiler has no electrical power, meaning the controls and display are completely dead.
Why it happens: This fault occurs when the electrical supply to the boiler's internal brain has been interrupted or a critical component has failed. The most common reason is a blown fuse on the main circuit board or a failure of the internal transformer which converts power for the display. In some cases, it can be caused by an external issue like a tripped circuit breaker or a blown fuse in the wall switch.
Check if the boiler's electrical isolation switch is turned on.Inspect your home's main fuse box to see if a circuit breaker has tripped.Check the fuse in the boiler's fused spur switch, usually located on the wall nearby.
Your boiler has stopped working and entered a safety shutdown mode, meaning it will not provide heating or hot water until it is reset or repaired.
Why it happens: This fault occurs when the boiler has tried to ignite several times but failed to detect a stable flame, leading the system to shut down for safety. The most common reasons are a lack of gas reaching the burner or a worn-out component failing to spark or sense the flame correctly. It essentially means the boiler’s internal computer has lost confidence that it can burn fuel safely.
Locate the reset button or control knob on the front panelTurn the knob to the 'Reset' position or press the reset button for 5 secondsWait for the boiler to attempt to restart; if the code returns, contact a professional
Your boiler has tried to light several times but has been unable to produce a flame, meaning your heating and hot water will not work.
Why it happens: This fault occurs when the boiler fails to detect a steady flame after several attempts to ignite the gas. The most common reasons include a lack of gas supply to the unit, a worn-out ignition spark, or a build-up of carbon on the internal probes that monitor the combustion process.
Check if other gas appliances, like a hob, are working to ensure gas is reaching the property.Verify that your gas prepayment meter has credit.Press and hold the reset button for five seconds to see if the system restarts.
Your boiler has become too hot and has automatically shut itself down to prevent damage.
Why it happens: This fault occurs when the internal water temperature exceeds a safe limit, causing the boiler to shut down for safety. The most common reasons are a pump failure that stops water from moving or a blockage in the system pipes that prevents heat from being carried away from the boiler quickly enough.
Wait for the boiler to cool down completely for at least 30 minutes.Check that your radiator valves are open and not turned off.Locate the reset button on the control panel and press it firmly to restart the unit.
on the Potterton Envoy 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 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