329 Medium

ECA 329 Fault Code

The ECA 329 fault code means: your boiler's internal control system is confused because two separate components are trying to perform the same task at the same time.. 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: Additional module - mix group, same function
Typical repair cost £120-250 (including labour)

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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ECA models that show the 329 fault code

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

Source

ECA 329 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