BoilerFaultCodesBaxi 127 Fault Code
The Baxi 127 fault code means: your boiler has failed to heat the water in your cylinder to a high enough temperature to kill off potentially harmful bacteria.. It appears on 3 Baxi models in our database.
Technical description: Legionella (cause of Legionnaires’ disease) protection temperature not reached
DIY fix possible
Check that your hot water cylinder thermostat is set to at least 60°CEnsure your boiler control knob is not turned to the 'minimum' or 'off' positionCheck your programmer to ensure the hot water heating window is long enough (at least 1 hour) for the tank to reach full temperature
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Baxi models that show the 127 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Baxi 127 fault code information on this page is sourced and cross-checked against the official Baxi service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026