BoilerFaultCodesThe 6 most common faults
Your boiler has stopped working because the water pressure inside the heating system has dropped too low.
Locate the filling loop, which is a flexible silver pipe under the boiler.Open the valves at both ends of the filling loop to allow cold mains water to enter the system.Watch the pressure gauge on the front of the boiler until the needle reaches the green zone (typically 1.0 to 1.5 bar).Close both valves firmly and ensure the loop is disconnected if it is of a non-permanent type.
Your boiler is struggling to pump water around your heating system quickly enough, causing the water inside to get hot too fast and triggering a safety shutdown.
Check that all radiator valves throughout your home are fully open.Inspect the boiler pressure gauge to ensure it is within the normal green operating range (usually 1.0 to 1.5 bar).Turn the boiler off at the fused spur and back on again after 30 seconds to attempt a system reset.
Your boiler has stopped heating because the water pressure inside the system has dropped too low.
Locate the filling loop, which is usually a flexible metal hose connected to two valves under the boiler.Open the valves slowly to allow mains cold water into the system until the pressure gauge reads between 1.0 and 1.5 bar.Close both valves firmly and check the display to confirm the error has cleared.
Your boiler has detected that it is running too hot or that the pressure in your heating system is too low, so it has purposefully shut down to protect itself from damage.
Full guide for b...Your boiler is failing to light the flame needed to produce heat or hot water.
Full guide for E 02Your boiler has switched itself off because the water inside is running much hotter than it should be.
Full guide for B 18on the Keston C90 / C110
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