BoilerFaultCodesThe 6 most common faults
Your boiler has detected that water is leaving the unit much hotter than when it returns, suggesting that the water isn't circulating through your radiators properly.
Ensure all radiator valves (TRVs) are fully openCheck that the boiler pressure is between 1 and 1.5 bar on the gaugeBleed all radiators to remove trapped air pockets
Your boiler is heating up too quickly and has temporarily shut down to prevent overheating, usually because the water cannot circulate properly through your radiators.
Check that your boiler pressure is between 1 and 1.5 bar on the gauge.Ensure at least two or three radiators have their valves fully open.Bleed your radiators to remove any trapped air that might be blocking water flow.
Your boiler has shut down because it has detected that the water inside has become too hot, usually due to a lack of circulation.
Ensure all radiator valves (TRVs) are turned to the highest settingCheck that the boiler pressure is between 1 and 1.5 bar on the gaugeWait 30 minutes for the unit to cool down and press the Reset button
Your boiler has detected that water is not moving through the system properly, often because the water pressure is too low.
Check the pressure gauge on the front of the boiler; it should be between 1 and 1.5 bar.Locate the filling loop (the silver braided hose) underneath the boiler.Open the valves slowly to top up the water pressure until the gauge reaches 1.2 bar, then close them tightly.Restart the boiler to clear the fault.
Your boiler has detected that the water pressure in your radiators is too low for the system to work safely, so it has turned itself off.
Locate the flexible filling loop under the boiler with the two blue-handled taps.Slowly open both taps one at a time until you hear water flowing.Watch the pressure gauge on the front of the boiler until it reaches between 1.0 and 1.5 bar, then close both taps fully.
Your boiler has been told to stop running by an external safety device or control, such as a thermostat or a condensation pump, which has detected an issue.
Check if your thermostat or programmer is calling for heat and has working batteries.If you have a condensate pump, check if it is full or blocked, as it may have triggered a safety shut-off.Reset the boiler using the control knob to see if the error clears.
on the Baxi 800
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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