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 to operate safely.
What to try first
Locate the filling loop (a silver flexi-hose with valves) underneath the boiler or nearby pipework.Open the valves slowly to allow mains water into the system while watching the pressure gauge on the front of the boiler.Stop filling once the needle reaches 1.5 bar on the gauge and ensure both valves are firmly closed.
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 safely shut itself down to prevent overheating.
Full guide for E2003
E28 High Engineer
Your boiler's computer module has been identified as the wrong type for your specific heating system, preventing it from operating correctly.
Full guide for E2804
E50 High Engineer
Your boiler is struggling to accurately measure the temperature of the water being heated for your taps and shower, so it has stopped working to prevent overheating.
Full guide for E5005
E110 High Engineer
Your boiler has detected that it is overheating and has automatically switched itself off to prevent damage.
Full guide for E11006
E125 High Engineer
Your boiler is struggling to pump water around your heating system, which is preventing it from heating up your home or water properly.
Full guide for E125on the Main Ecoinstaller 2
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