BoilerFaultCodesThe 6 most common faults
01
26 High DIY-safe
Your boiler is struggling to circulate water, likely because there is not enough pressure in the system or the internal pump has stopped working.
What to try first
Check your boiler's pressure gauge on the front panel; if it is below 1 bar, you may need to top it up using the external filling loop.Ensure your system pressure is set to roughly 1.5 bar.If the pressure is correct, ensure your heating controls and room thermostat are set to 'on' to see if the pump triggers.
02
27 High DIY-safe
Your boiler is struggling to circulate water, likely because there is not enough water inside the system or the internal pump has stopped working.
What to try first
Check your pressure gauge; if it is below 1 bar, top up your boiler using the filling loop until it hits 1.5 bar.Turn off the power to the boiler for 30 seconds to perform a hard reset.Check if any radiators are cold at the bottom, which may indicate trapped air needing a bleed.
03
24 High Engineer
Your boiler is failing to light the internal flame, which could be due to a blockage in the waste water pipe or an issue with the gas ignition system.
Full guide for 2404
28 High Engineer
Your boiler has lost the ability to accurately measure the temperature of the water circulating through your radiators, so it has shut down to prevent overheating.
Full guide for 2805
29 High Engineer
Your boiler has stopped working because it is unable to accurately measure the temperature of the water used for your radiators.
Full guide for 2906
neon flashing High Engineer
Your boiler has detected a general internal fault that prevents it from starting, meaning you currently have no heating or hot water.
Full guide for neon flashingon the Baxi 105e
Central heating pumpPressure relief valvePressure gaugePressure switchIgnition electrodeFlame rectification probe
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