BoilerFaultCodesThe 6 most common faults
01
E119 High DIY-safe
Your boiler has temporarily stopped working because the water pressure inside the system has dropped too low.
What to try first
Locate the filling loop valves underneath your boiler.Open the valves gently to allow water to enter the system until the pressure gauge reads between 1.0 and 1.5 bar.Close both valves tightly and reset the boiler.
02
E20 High Engineer
Your boiler has detected a problem with the sensor that measures the temperature of your heating system, so it has temporarily stopped working to be safe.
Full guide for E2003
E28 High Engineer
Your boiler has detected that the electronic control board currently installed is not the correct model or version specified for your specific appliance.
Full guide for E2804
E50 High Engineer
Your boiler is struggling to accurately measure the temperature of your hot water because a sensor is failing, which usually stops hot water from working properly.
Full guide for E5005
E125 High Engineer
Your boiler has detected that water is not flowing properly through the internal heating system.
Full guide for E12506
E133 High Engineer
Your boiler has stopped working because it cannot detect a steady flame to keep it burning, which usually points to an issue with the gas supply or the ignition.
Full guide for E133on the Main Eco Elite Combi 25/30
Water pressure switchPressure relief valveExpansion vesselCentral Heating NTC ThermistorWiring 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