BoilerFaultCodesThe 6 most common faults
Your boiler has stopped working because the amount of water inside your heating system has dropped below the required level.
Locate the filling loop, which is a silver braided flexible hose connected between two pipes under your boiler.Open the small valve or tap on the loop to let water flow into the system until the pressure gauge reads between 1.0 and 1.5 bar.Fully close both valves on the loop to stop the water flow and prevent over-pressurisation.
Your boiler is not receiving the correct signal from your wall thermostat, so it has stopped heating your home to prevent an incorrect temperature.
Check the batteries in your wireless wall thermostat and replace them if necessaryEnsure your thermostat receiver box is receiving power and the display is litTurn off your boiler at the main spur for 30 seconds to restart the control system
Your boiler has stopped working because the water pressure inside the system has dropped too low to operate safely.
Locate the filling loop (a flexible metal hose with one or two valves) connected to the underside of the boiler.Open the valves slowly to allow water into the system while watching the pressure gauge on the front of the boiler.Close the valves firmly once the needle reaches 1.5 bar and check for any signs of leaks.
Your boiler has tried to start five times but failed to ignite, so it has safely shut itself down to prevent a build-up of unburnt gas.
Full guide for Ignition LockoutYour boiler has attempted to restart itself multiple times in a short window because it keeps encountering a recurring problem, and it has now locked itself out to prevent damage.
Full guide for Too Many RestartsYour boiler has detected that it is getting too hot and has automatically switched itself off to prevent any damage.
Full guide for Overheat Lockouton the Keston C30 / C35
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
Avoid the next call-out bill
Monthly cover means no unexpected bills when your boiler breaks down.
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