BoilerFaultCodesThe 6 most common faults
Your boiler has become too hot and has automatically shut down for safety, preventing internal damage.
Switch off the boiler and wait at least 30 minutes for it to cool down completely.Check that your radiator valves are open and your boiler pressure is between 1.0 and 1.5 bar.Turn the selector knob to the 'Reset' position for five seconds, then turn it back to your desired setting.
Your boiler has stopped working because the water pressure inside the system has dropped too low to operate safely.
Locate the filling loop (usually a silver braided hose with small valves) underneath or near the boiler.Slowly open one or both valves until you hear water entering the system.Watch the pressure gauge and close the valves once the needle reaches between 1.0 and 1.5 bar.
Your boiler has detected that hot water is not moving around the system correctly, causing it to shut down to prevent overheating.
Check that your system pressure is between 1.0 and 1.5 bar on the pressure gauge.Ensure all radiator valves are fully open to allow water to flow.If you have recently bled your radiators, top up the water pressure using the filling loop.
Your boiler has failed to light, likely because gas isn't reaching the burner or the spark isn't igniting the flame.
Check if your gas meter has credit (if on a prepayment meter)Check that other gas appliances, like a cooker, are working correctlyPress and hold the Reset button for five secondsCheck if the condensate pipe (the white plastic pipe outside) is frozen
The water isn't moving through your boiler properly or is heating up too quickly, causing the system to shut down to prevent overheating.
Check that your radiator valves are fully openEnsure there is enough water pressure in the system (typically 1.0 to 1.5 bar)Try bleeding your radiators to remove any trapped air
Your boiler has lost its ability to accurately measure the temperature of the water being heated for your radiators, causing the system to shut down for safety.
Full guide for E20on the Potterton Promax Combi ErP
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