How much does it cost to fix Baxi error code H.01 – .08?

Typical repair cost for the Baxi H.01 – .08 fault is £120-350 including labour.

H.01 – .08 High

Baxi H.01 – .08 Fault Code

Q: What does the Baxi H.01 – .08 fault code mean?

Your boiler is overheating because water isn't moving through the system quickly enough to be cooled down.

Also written as H0108 — same fault.

The Baxi H.01 – .08 fault code means: your boiler is overheating because water isn't moving through the system quickly enough to be cooled down.. It appears on 24 Baxi models in our database.

Technical description: Sensor fault, flow temperature increasing too fast in heating mode or insufficient circulation.

What causes the Baxi H.01 – .08 fault?

This fault occurs when the water inside your boiler heats up too quickly because it isn't being pumped away and into your radiators fast enough. The most common reasons are a pump that has seized up or a build-up of sludge and debris in the system that is restricting the flow of water.

This fault is more frequent in autumn when the heating is turned back on after a long summer break, as internal pump parts can seize up from lack of use.

Typical repair cost £120-350 (including labour)

DIY fix possible

Check that your boiler pressure is between 1 and 1.5 bar on the gaugeEnsure all radiator valves are fully openRestart the boiler using the reset button

Find a Gas Safe engineer

Search the official register for a qualified engineer in your area.

Gas Safe Register →

Baxi models that show the H.01 – .08 fault code

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

Source

Baxi H.01 – .08 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