BoilerFaultCodesThe 6 most common faults
Your boiler has lost the water pressure it needs to circulate heat around your home, so it has turned itself off to prevent damage.
Locate the external filling loop, usually a small silver braided hose with one or two valves located underneath the boiler.Slowly open the valve(s) to allow mains water into the heating system until the pressure gauge on the front of the boiler reads between 1.0 and 1.5 bar.Close the valve(s) tightly to ensure no water continues to enter the system.
Your boiler has detected that the water leaving it is significantly hotter than the water returning, suggesting that heat isn't circulating properly through your radiators.
Check your boiler's pressure gauge to ensure it is between 1.0 and 1.5 barIf the pressure is low, top it up using the external filling loopEnsure all radiator valves are fully open and there is no trapped air by bleeding radiators
Your boiler has stopped working because the water pressure inside your heating system has dropped too low to function safely.
Locate the filling loop (a silver braided hose) underneath the boiler.Open the valves on both ends of the loop to allow water into the system.Watch the pressure gauge on the front of the boiler until the needle reaches the green zone (usually 1.0 to 1.5 bar).Close both valves tightly and ensure the pressure remains stable.
Your boiler has tried to start up four times but failed to get the gas flame going, so it has locked itself for safety.
Full guide for E.04.10Your boiler is struggling to detect the water pressure inside the system because the sensor that monitors it has stopped communicating correctly.
Full guide for H.00.42Your boiler has detected that water is not moving through your heating system properly and has temporarily stopped itself to prevent overheating.
Full guide for H.01.18on the Baxi Assure 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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