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 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
Your boiler has stopped working because the water pressure inside the system is too low and needs to be topped up.
Locate the filling loop (usually a silver flexible hose) underneath the boiler.Open the small taps on the loop slowly until you hear water flowing and the pressure gauge reaches 1.0 to 1.5 bar.Close both taps tightly and restart the boiler if necessary.
Your boiler was running but the flame went out unexpectedly, causing the system to stop working for safety.
Check if other gas appliances, like a hob, are working to ensure gas is reaching the propertyCheck that your gas meter has credit if you use a prepay systemCheck the condensate pipe (the white plastic pipe outside) isn't frozen or blockedRestart the boiler using the Reset button
Your boiler is not turning on because it has lost communication with your wall-mounted thermostat.
Locate your wall-mounted room thermostat or programmer.Replace the batteries with new, high-quality alkaline batteries.Check that the thermostat is set to a temperature higher than the current room temperature to call for heat.
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.
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