How much does it cost to fix Baxi error code H.01 – .05?

Typical repair cost for the Baxi H.01 – .05 fault is £120-280 including labour.

H.01 – .05 High

Baxi H.01 – .05 Fault Code

Q: What does the Baxi H.01 – .05 fault code mean?

Your boiler has detected that the water is heating up too quickly or isn't circulating properly through the system.

Also written as H0105 — same fault.

The Baxi H.01 – .05 fault code means: your boiler has detected that the water is heating up too quickly or isn't circulating properly through the system.. It appears on 24 Baxi models in our database.

Technical description: Difference between the flow and return temperature is too high, sensor error or insufficient circulation.

What causes the Baxi H.01 – .05 fault?

This fault occurs when heat isn't being moved away from the boiler's internal heat exchanger fast enough, causing a rapid temperature spike. The most common reasons are a failing circulation pump, a blockage in the system pipework, or air trapped within the unit preventing water flow.

This issue often surfaces during the first cold snap of autumn when the heating is turned on after being dormant all summer, which can cause the pump to seize.

Typical repair cost £120-280 (including labour)

DIY fix possible

Check that the boiler pressure is between 1 and 1.5 bar on the gaugeEnsure all radiator valves are fully openCheck for any visible leaks around the boiler or pipeworkRestart the boiler using the reset button

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Baxi models that show the H.01 – .05 fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Baxi H.01 – .05 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