812 High

ECA 812 Fault Code

The ECA 812 fault code means: your boiler has detected that the water returning to the unit is significantly hotter than the safe limit, causing it to shut down to prevent damage.. 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 £90-280 (including labour)

DIY fix possible

Check all radiator valves (TRVs) are fully openEnsure the central heating pump is not blocked or stuckCheck that the bypass valve is not closed too tightly

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ECA models that show the 812 fault code

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

Source

ECA 812 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