E03 High

ECA E03 Fault Code

The ECA E03 fault code means: your boiler has switched itself off because internal sensors have detected that the water inside the unit is getting too hot, preventing potential damage.. It appears on 4 ECA 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: High temperature limit (overheating) lockout
Typical repair cost £120-350 (including labour)

DIY fix possible

Check that your radiator valves are fully open to allow water to circulate.Ensure your system water pressure is between 1.0 and 1.5 bar on the gauge.Restart the boiler using the reset button once the unit has cooled down.

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ECA models that show the E03 fault code

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

Source

ECA E03 fault code information on this page is sourced and cross-checked against the official ECA service / installation manuals for each affected model.

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