How much does it cost to fix Ferroli error code A03?

Typical repair cost for the Ferroli A03 fault is £120-300 including labour.

A03 High

Ferroli A03 Fault Code

Q: What does the Ferroli A03 fault code mean?

Your boiler has likely overheated because the water isn't moving through the system properly or a safety sensor has detected a temperature that is too high.

The Ferroli A03 fault code means: your boiler has likely overheated because the water isn't moving through the system properly or a safety sensor has detected a temperature that is too high.. It appears on 9 Ferroli models in our database.

Technical description: High limit protection – possible flow temperature sensor not active or incorrectly located, no system circulation

What causes the Ferroli A03 fault?

This fault occurs when the water inside the boiler exceeds a safe temperature, triggering a safety shutdown. The most common reasons are a pump failure that prevents water from moving, or a buildup of debris and sludge that blocks the heat exchanger.

This issue is more frequent during the first cold spell of autumn, when pumps that have been idle all summer often seize up upon being restarted.

Typical repair cost £120-300 (including labour)

DIY fix possible

Check that your radiator valves and isolation valves are fully openEnsure your system pressure is topped up to between 1 and 1.5 barPress the Reset button on the control panel to see if the fault clears

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Ferroli models that show the A03 fault code

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

Source

Ferroli A03 fault code information on this page is sourced and cross-checked against the official Ferroli service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026