BoilerFaultCodesThe 6 most common faults
Your boiler has lost all power and is completely shut down, meaning it cannot provide any heating or hot water.
Check your home's consumer unit (fuse box) to ensure the boiler's circuit breaker hasn't tripped.Ensure the fused spur switch located near the boiler is turned on.Check that the fuse inside the fused spur switch has not blown.
Your boiler has detected that it is heating up too quickly or getting too hot, usually because the water isn't moving through the system properly.
Check that your pump is running and hasn't seizedEnsure all radiator valves are open to allow water flowCheck that the system pressure is at the correct level (usually 1.0 to 1.5 bar)Bleed all radiators to remove trapped air pockets
Your boiler has lost its flame while it was running, which means it has stopped providing heating and hot water for safety.
Check that your gas emergency control valve is open and you have credit on your gas meter.Verify if other gas appliances in your home, such as a hob, are working correctly.Press the reset button or turn the selector switch to 'R' for five seconds to attempt a restart.
Your boiler has stopped heating because it is struggling to accurately measure the water temperature or the water isn't moving through the system correctly.
Check that all radiator valves and boiler isolation valves are fully openEnsure your thermostat is calling for heat and has working batteriesReset the boiler by turning the selector switch to the reset position for five seconds
Your boiler has shut down because it has detected it is getting too hot, likely due to a lack of water circulation or a blocked flue.
Check that all radiator valves are fully open (at least two or three)Check that the external system pump is running if accessibleTurn the selector knob to the 'Reset' position for five seconds and release
Your boiler is trying to start up but cannot light the gas or keep the flame burning, so it has shut down for safety.
Check if other gas appliances in your home, like a hob, are still working to confirm gas supply.If it is freezing outside, check that your external white plastic condensate pipe hasn't frozen.Press the Reset button or turn the selector knob to 'R' for five seconds and release.
on the Baxi 800 Heat (range)
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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