425 High

ECA 425 Fault Code

The ECA 425 fault code means: your boiler has detected that the water returning to the unit is far too hot, causing it to shut down to prevent overheating.. It appears on 1 ECA 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: Boiler return temperature> [3925.1] TempRetMaxSLTSec
Typical repair cost £120-280 (including labour)

DIY fix possible

Check that all radiator valves are fully open to allow water to flow.Ensure the central heating system is not blocked by heavy sludge or debris.Verify that the circulation pump is running and hasn't seized.

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ECA models that show the 425 fault code

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

Source

ECA 425 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