BoilerFaultCodesThe 6 most common faults
Your boiler is failing to light the flame needed to heat your home, which is often caused by a temporary interruption in the gas supply or an issue with the ignition system.
Check that your gas emergency control valve is in the 'on' positionIf you have a prepayment meter, ensure you have credit and the meter is activePress the reset button or turn the control knob to 'R' for five seconds and release
Your boiler has shut down because its internal temperature got too high, causing a safety switch to trigger and prevent damage.
Check that your radiator valves are open and not turned off.Ensure there is no air trapped in your radiators by bleeding them.Wait for the boiler to cool down and then press the 'Reset' button.
Your boiler has stopped working because there is not enough water pressure in the system to run safely.
Locate the external filling loop (usually a silver braided hose with small black lever handles) under or near the boiler.Slowly open both lever valves until you hear water flowing and watch the pressure gauge.Once the gauge reaches 1.5 bar, close both valves tightly and reset the boiler.
Your boiler has failed to light the gas flame or cannot detect that the flame is burning, causing the system to shut down for safety.
Check if your gas supply is active by testing another gas appliance like a hob.Locate the red 'Flame Failure' button on the front control panel.Press and hold the button for a few seconds to reset the boiler.
Your boiler has become too hot and has shut itself down as a safety precaution to prevent damage.
Check that all your radiator valves are open to allow water to flow.Ensure your system pressure is at the correct level (usually between 1 and 1.5 bar).Press the white Reset Button on the front of the boiler.
Your boiler is using a combination of flashing or steady lights to signal exactly what is wrong with the system, ranging from simple pressure issues to internal component failure.
Check if the gas supply is turned on and credit is on the meterEnsure the system pressure is between 1.0 and 1.5 bar on the gaugeTurn the selector switch to the reset position for five seconds and release
on the Baxi Promax 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