BoilerFaultCodesThe 6 most common faults
Your boiler has stopped working because the water pressure inside the system has dropped too low to operate safely.
Locate the external filling loop, usually two silver valves connected by a braided metal hose underneath the boiler.Slowly open the valves to allow mains water into the system while watching the pressure gauge on the front display.Close both valves tightly once the needle reaches the green zone, ideally around 1.5 bar.
Your boiler has stopped working because the water pressure inside your heating system has dropped too low.
Locate the external filling loop, usually a small silver braided hose with one or two valves located underneath the boiler.Gradually open the valve(s) to allow water into the system while watching the pressure gauge on the front panel.Stop filling exactly when the needle reaches the green zone, typically between 1.0 and 1.5 bar, and ensure the valve is tightly closed.
Your boiler has lost the ability to accurately measure the temperature of the water circulating through your radiators, so it has shut down to prevent overheating.
Full guide for E20Your boiler has lost the ability to measure the temperature of your hot water, so it has shut down to prevent overheating.
Full guide for E50Your boiler has detected that it is overheating and has automatically switched itself off to prevent damage or potential danger.
Full guide for E110Your boiler is struggling to move water through the system, either because there isn't enough water pressure or because the pump is having trouble circulating it.
Full guide for E125on the Potterton Titanium
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