How much does it cost to fix Baxi error code H.03 – .01?

Typical repair cost for the Baxi H.03 – .01 fault is £250-450 including labour.

H.03 – .01 High

Baxi H.03 – .01 Fault Code

Q: What does the Baxi H.03 – .01 fault code mean?

Your boiler's computer parts are having trouble talking to each other, which means the system cannot operate for heating or hot water.

Also written as H0301 — same fault.

The Baxi H.03 – .01 fault code means: your boiler's computer parts are having trouble talking to each other, which means the system cannot operate for heating or hot water.. It appears on 24 Baxi models in our database.

Technical description: Communication error with the printed circuit board (PCB)

What causes the Baxi H.03 – .01 fault?

This fault occurs when the boiler's internal control board loses its connection with the sensors and valves that regulate heating. The most common reasons are a loose internal wire connection, moisture getting onto the electronics, or a component failure within the circuit board itself.

Typical repair cost £250-450 (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 27 April 2026