BoilerFaultCodesThe 6 most common faults
Your boiler has detected a problem safely discharging exhaust gases or removing waste water, causing it to shut down for safety.
Why it happens: This fault occurs when the boiler's internal safety sensors detect that the exhaust gases are too hot or cannot escape the property correctly. It is often triggered by a breakdown in the sensor that monitors flue temperatures, or a physical blockage in the pipe that carries waste water away from the unit. When the system can no longer safely vent heat or clear condensation, it shuts down to prevent internal damage.
Check the external plastic condensate pipe for signs of freezing or blockageGently pour warm water over the external pipe if it is frozenEnsure the external flue terminal on your wall is not obstructed by debris or plantsReset the boiler once by turning the selector knob to 'R' for five seconds
Your boiler has reached an excessively high temperature and has shut down as a safety precaution to prevent damage.
Why it happens: This fault occurs when the water inside the boiler gets too hot, triggering a safety switch to shut the system down. The most common reasons are a pump failure preventing water from moving through the unit, or a internal blockage like air or sludge that is trapping heat in the heat exchanger.
Check that all radiator valves are fully open to allow water to circulate.Ensure your system pressure is between 1.0 and 1.5 bar on the front gauge.Try resetting the boiler by turning the selector knob to the 'R' position for five seconds.
Your boiler has lost water pressure and has stopped working to protect itself from damage.
Why it happens: This fault occurs when the water pressure inside your heating system drops below a safe level, causing the boiler to shut down to prevent overheating. The most common reason is a small leak in the pipework or radiators, though it can also happen if you have recently bled your radiators and haven't topped the water back up.
Locate the filling loop (the flexible braided hose) underneath or near the boiler.Slowly open the tap or valve(s) on the loop while watching the pressure gauge.Close the tap or valve(s) tightly once the gauge reaches between 1 and 1.5 bar.
Your boiler is struggling to move water around the system properly, which is causing it to shut down to prevent overheating.
Why it happens: This fault occurs when the boiler detects that water is not moving through the internal pipes quickly enough to take the heat away from the burner. The most common reasons are a failed pump that can no longer push the water, or a blockage caused by a build-up of sludge and debris in the system. Because the heat cannot escape, the boiler shuts down as a safety precaution to prevent the internal components from melting or cracking.
Check that all radiator valves (TRVs) are fully openEnsure your system pressure is between 1.0 and 1.5 bar on the gaugeTry resetting the boiler to see if the error clears
Your boiler is not receiving enough gas or is struggling to light the flame needed to heat your water and radiators.
Why it happens: This fault occurs when the boiler tries to ignite three times but fails to establish or maintain a steady flame. The most common reasons are an interruption in the gas supply, a blocked pipe, or a component inside the boiler being unable to create the spark needed to light the gas.
Check that your gas emergency control valve is open and any prepaid gas meter has credit.Ensure other gas appliances, like a hob, are working to confirm gas supply to the property.If it is freezing outside, check if your external condensate pipe has frozen and gently thaw it with warm water.Press the Reset button for five seconds to attempt to restart the boiler.
Your boiler has detected that water is not circulating correctly through the system before the burner ignites.
Why it happens: This fault occurs when the boiler's internal sensors detect that water isn't moving through the unit quickly enough before it attempts to fire up. The most common reason is a seized or failing circulation pump, though it can also be caused by air trapped in the heat exchanger or a blockage in the system pipework. Because the heat cannot be carried away from the burner, the boiler shuts down to prevent internal damage from overheating.
Check that your system pressure is between 1.0 and 1.5 bar on the pressure gaugeEnsure all radiator valves and isolation valves under the boiler are fully openBleed your radiators to remove any trapped air pockets that may be blocking flow
on the Baxi Platinum Heat
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