A03 High

Euroterm A03 Fault Code

The Euroterm A03 fault code means: your boiler has become too hot and has shut itself down as a safety precaution to prevent internal damage.. It appears on 1 Euroterm model 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: Overtemperature protection
Typical repair cost £120-300 (including labour)

DIY fix possible

Wait for the boiler to cool down for at least 30 minutesCheck that all radiator valves are fully openCheck the boiler pressure gauge and top up to 1.5 bar if it is lowPress the Reset button on the control panel

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Euroterm models that show the A03 fault code

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

Source

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

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026