BoilerFaultCodesThe 6 most common faults
01
E119 High DIY-safe
Your boiler has stopped working because the water pressure inside the heating system has dropped too low to operate safely.
What to try first
Locate the filling loop (usually a silver braided hose under the boiler)Open the valves to allow mains water into the system until the pressure gauge reads between 1.0 and 1.5 barClose the valves tightly and restart the boiler
02
E20 High Engineer
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 E2003
E28 High Engineer
Your boiler has detected that the internal computer board installed does not match the model requirements, preventing it from functioning correctly.
Full guide for E2804
E50 High Engineer
Your boiler has lost the ability to accurately measure the temperature of its hot water, so it has shut down to prevent overheating.
Full guide for E5005
E110 High Engineer
Your boiler has detected that it is running too hot and has automatically shut itself down to prevent damage.
Full guide for E11006
E125 High Engineer
Your boiler is struggling to pump water around your heating system, so it has safely shut down to prevent overheating.
Full guide for E125on the Main Eco Elite System
Pressure relief valvePressure sensorExpansion vesselCentral Heating NTC 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