BoilerFaultCodesThe 6 most common faults
01
E119 High DIY-safe
Your boiler has stopped working because the water pressure inside the system has dropped too low.
What to try first
Locate the external filling loop, usually two silver flexible hoses with small valves underneath the boiler.Open the valves slowly to allow mains water into the system until the pressure gauge reads between 1.0 and 1.5 bar.Close both valves tightly to stop the flow once the correct pressure is reached.
02
E20 High Engineer
Your boiler has stopped heating your home or water because it is failing to receive a proper temperature signal from its internal sensor.
Full guide for E2003
E28 High Engineer
Your boiler's computer system does not recognise the specific electronic board installed, preventing the unit from operating correctly.
Full guide for E2804
E50 High Engineer
Your boiler has lost its ability to accurately measure the temperature of the water used for your taps, causing it to shut down for safety reasons.
Full guide for E5005
E110 High Engineer
Your boiler has detected that it is getting too hot and has automatically shut itself down to prevent damage.
Full guide for E11006
E125 High Engineer
Your boiler is struggling to move water around your heating system, which is keeping it from heating your home properly.
Full guide for E125on the Main System 18 HE
Pressure relief valvePressure gaugeFilling loopNTC Temperature SensorWiring HarnessPrinted Circuit Board (PCB)
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 Main 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