393 Medium

ECA 393 Fault Code

The ECA 393 fault code means: your boiler has lost communication with its room thermostat, meaning it cannot detect the temperature of your home to know when to heat up.. It appears on 1 ECA model in our database.

Book a service

This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

Technical description: Room kontrol device 3
Typical repair cost £100-250 (including labour)

DIY fix possible

Check that your room thermostat or smart controller has fresh batteries.Ensure the thermostat is powered on and within range of the receiver unit.Try power-cycling the boiler by turning it off at the fused spur for 60 seconds before switching it back on.

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ECA models that show the 393 fault code

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

Source

ECA 393 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