BoilerFaultCodesThe 6 most common faults
Your boiler has stopped working because the water pressure inside your heating system has dropped too low.
Locate the filling loop (a silver flexible hose or small integrated valve) under your boiler.Open the valve(s) slowly to allow water into the system while watching the pressure gauge on the front of the boiler.Stop when the needle reaches between 1 and 1.5 bar, then ensure the valve is firmly closed.
Your boiler has stopped working because the water pressure inside the heating system has dropped too low.
Locate the external filling loop, which is usually a flexible silver hose connected between two valves near your boiler or hot water cylinder.Open the valves slowly to allow water to enter the system until the pressure gauge on the boiler shows between 1 and 1.5 bar.Close both valves tightly and remove the filling loop if required by your specific setup.
Your boiler has detected that the water pressure inside your heating system is too high, which could prevent it from working safely.
Locate the filling loop (a silver flexi-hose) connected to your heating pipes.Ensure both valves on the filling loop are turned firmly to the closed position.If the pressure remains high, cautiously bleed a radiator in the house to release some water until the gauge drops to between 1 and 1.5 bar.
Your boiler has failed to start up after several attempts, meaning it is currently unable to provide heating or hot water until the ignition issue is resolved.
Full guide for E02Your boiler is struggling to keep its flame lit while in operation, which means it has safely shut itself down to prevent any issues.
Full guide for E04Your boiler has automatically shut down because the water inside it has become dangerously hot.
Full guide for E12on the Keston Qudos 28S
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 Keston 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