BoilerFaultCodesThe 6 most common faults
Your boiler has failed to ignite or has lost its flame because it isn't receiving the gas it needs to stay lit.
Check that your gas emergency control valve is in the 'on' position.If you have a prepay meter, check that you have sufficient credit and that the meter is not 'locked'.Check if other gas appliances in your home, such as a hob, are working correctly.Restart the boiler by pressing the reset button for five seconds.
Your boiler has stopped working because the amount of water circulating inside your heating system has dropped below the required level.
Locate the filling loop (a silver flexible hose) underneath the boiler.Open the valves at both ends of the hose to allow water into the system.Watch the pressure gauge on the front of the boiler until the needle reaches 1.5 bar, then firmly close both valves.
Your boiler has lost its flame while it was running, meaning it cannot stay alight to provide heating or hot water.
Check that your gas supply is active (e.g., check other gas appliances or your meter credit)Restart the boiler by pressing the reset button for five secondsCheck if the condensate pipe (the plastic pipe leading outside) is frozen or blocked
Your boiler has detected a problem with the temperature sensor on the central heating system, so it has temporarily stopped working to prevent overheating.
Full guide for 15Your boiler has detected that water is not moving correctly through the internal heating system, preventing it from heating your home or water safely.
Full guide for 125Your boiler has stopped working because it cannot light its internal flame, which is usually due to an issue with the gas supply or the ignition system.
Full guide for 133on the Baxi 818 System
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 Baxi 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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