H:03.01 High

Baxi H:03.01 Fault Code

Also written as H0301 — same fault.

The Baxi H:03.01 fault code means: your boiler's main control panel is having trouble sending messages to the unit's brain, which means the boiler cannot operate properly.. It appears on 3 Baxi models in our database.

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description: Communication error with the HMI PCB
Typical repair cost £150-300 (including labour)

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Baxi models that show the H:03.01 fault code

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

Source

Baxi H:03.01 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