BoilerFaultCodesThe 6 most common faults
Your boiler has failed to light, which means your heating and hot water will not work until the gas flow or ignition is restored.
Why it happens: This fault occurs when the boiler's control system attempts to light the burner but fails to detect a flame after several attempts. The most common reasons are a lack of gas reaching the appliance, a worn ignition spark electrode that cannot create a flame, or a faulty gas valve that isn't opening correctly.
Check that your gas meter has credit and that the external gas isolation valve is turned on.Check if other gas appliances in your home, such as a hob, are working correctly.Press and hold the 'Reset' button for 2 seconds to see if the boiler restarts.
Your boiler has switched itself off because it has become too hot inside, usually due to a blockage or a pump failure preventing water from circulating.
Why it happens: This fault occurs when the water inside the boiler exceeds a safe temperature, triggering a safety switch to prevent damage. The most common reason is that the water isn't moving through the system quickly enough, often due to a failed pump, a blockage of sludge, or air trapped inside the heat exchanger.
Check that all radiator valves are fully open.Ensure there is enough water pressure displayed on the boiler gauge (typically 1.0 to 1.5 bar).Press and hold the reset button for five seconds once the boiler has cooled down.
Your boiler has detected that the water pressure is too low for it to operate safely, which is usually fixed by topping up the system.
Why it happens: This fault occurs when the internal sensor detects that there isn't enough water circulating in the system to operate safely. The most common reason is a gradual loss of pressure through tiny leaks or recently bled radiators, though it can also be caused by a faulty sensor or a failing expansion vessel.
Locate the filling loop (usually a silver flexible hose) underneath the boiler.Slowly open the valves until you hear water entering the system.Watch the pressure gauge and close the valves once it reaches 1.5 bar, then restart the boiler.
Your boiler has overheated, prompting a safety switch to shut the system down to prevent damage.
Why it happens: This fault occurs when the water inside the boiler reaches an unsafe temperature, triggering a safety sensor to cut the power. The most common reasons are a failed pump stopping water from moving or a blockage in the heat exchanger caused by a buildup of sludge and debris.
Check that all radiator valves are fully openEnsure the system pressure is between 1.0 and 1.5 barAllow the boiler to cool down and then press the 'Reset' button
Your boiler has detected that the water pressure in the system is too low to run safely.
Why it happens: This fault occurs when the internal sensor detects that the water pressure has dropped below the minimum level required for the boiler to operate. The most common reason is a small leak somewhere in your radiator system or air being released through a valve, which reduces the overall volume of water. Without enough water pressure, the boiler shuts down to prevent the heat exchanger from overheating or becoming damaged.
Locate the external or internal filling loop (usually silver flexible hoses with blue or black handles).Slowly open the valves until you hear water flowing into the boiler.Monitor the pressure gauge on the front of the boiler until it reaches between 1.0 and 1.5 bar, then close the valves tightly.The boiler should reset automatically, but you may need to press the 'R' or reset button if the code persists.
Your boiler has shut down because it is getting too hot inside, usually because the water isn't moving around the system properly.
Why it happens: This fault occurs when the water inside the boiler reaches an unsafe temperature because it isn't being moved away into your radiators or hot water tap quickly enough. The most common reason is that the internal pump has failed or is stuck, but it can also be caused by a large air bubble trapped in the pipework blocking the flow.
Check that all radiator valves are open and not turned off.Ensure there is enough water pressure in the system (typically 1.0 to 1.5 bar).Gently bleed your radiators to remove any trapped air that might be blocking water flow.
on the Potterton Gold Combi 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 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