How much does it cost to fix Baxi error code 127?

Typical repair cost for the Baxi 127 fault is £90-200 including labour.

127 Medium

Baxi 127 Fault Code

Q: What does the Baxi 127 fault code mean?

Your boiler has failed to heat the hot water tank to a high enough temperature to kill off bacteria, which is a safety routine it performs periodically.

The Baxi 127 fault code means: your boiler has failed to heat the hot water tank to a high enough temperature to kill off bacteria, which is a safety routine it performs periodically.. It appears on 26 Baxi models in our database.

Technical description: Legionella (cause of Legionnaires’ disease) protection temperature not reached

What causes the Baxi 127 fault?

This fault occurs when the boiler tries to perform its weekly safety cycle but fails to heat the water in your cylinder to the required 60°C within a set timeframe. The most common reason is a communication breakdown between the boiler and the hot water tank, often caused by a faulty sensor or a motorized valve that is stuck and preventing hot water from flowing to the cylinder.

Typical repair cost £90-200 (including labour)

DIY fix possible

Check that your hot water cylinder thermostat is not turned down too lowEnsure your hot water timer is set to allow the boiler enough time to complete a full heating cycleReset the boiler to see if the cycle completes successfully on the next attempt

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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 27 April 2026