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 external filling loop, usually a silver braided hose near the boilerSlowly open the valves on the loop to allow mains water into the heating systemWatch the pressure gauge on the front of the boiler until the needle reaches between 1.0 and 1.5 barClose both valves tightly and remove the filling loop if required
02
E20 High Engineer
Your boiler has lost the ability to accurately measure the temperature of the radiator water, so it has shut down to prevent overheating.
Full guide for E2003
E28 High Engineer
Your boiler's computer module has been identified as incompatible or was recently replaced incorrectly, preventing the system from operating safely.
Full guide for E2804
E50 High Engineer
Your boiler is struggling to accurately measure the temperature of the water being heated for your taps, so it has stopped providing hot water to ensure your safety.
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 has detected that hot water is not circulating properly around your heating system, so it has shut down to prevent overheating.
Full guide for E125on the Main Eco 24 HE
Pressure relief valvePressure transducerFilling loopCentral Heating NTC SensorWiring HarnessMain Printed 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