BoilerFaultCodesThe 6 most common faults
Your boiler has got too hot and has shut itself down as a safety precaution to prevent damage.
Check that all radiator valves are fully open to allow water flow.Ensure there is enough pressure in the system by checking the gauge (it should be between 1 and 1.5 bar).Press the reset button once the boiler has had at least 15 minutes to cool down.
Your boiler has tried to light several times but cannot establish a flame, meaning your heating and hot water will not work until the issue is resolved.
Check that your gas prepayment meter has credit (if applicable).Ensure the main gas supply valve is open.Check if other gas appliances in your home, like a hob, are working.Press the 'Reset' button on the boiler control panel.In freezing weather, check if the external condensate pipe is frozen and thaw it with warm water.
Your boiler's water pressure has dropped too low, which has caused it to stop working for safety reasons.
Locate the filling loop (usually a silver braided hose with small valves) underneath the boiler.Slowly open the valve(s) until you hear water entering the system.Watch the pressure gauge and close the valves tightly once the needle reaches between 1.0 and 1.5 bar.Reset the boiler by pressing the 'RE' button or turning the dial to 'Reset'.
Your boiler has started to light but the flame has gone out unexpectedly, causing the system to stop working for safety.
Check that your gas emergency control valve is open and you have credit on your meter.Check if other gas appliances in your home, like a hob, are working correctly.Restart the boiler by pressing the reset button for five seconds.
Your boiler has failed to light several times and has shut down for safety, meaning you currently have no heating or hot water.
Check if your gas supply is active by testing another gas appliance like a hob.Ensure your condensate pipe hasn't frozen if it is cold outside.Press the Reset button for five seconds to see if the boiler restarts.
Your boiler has switched itself off because it has detected it is getting too hot, usually caused by a lack of water flow through the system.
Check the pressure gauge and top up the water if it is below 1.0 barEnsure at least two radiators are fully turned on and their valves are openReset the boiler by pressing the reset button for five seconds
on the Keston Combi C30
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.
Affiliate links. We may earn a commission at no extra cost to you.