2128 Medium

Warmflow 2128 Fault Code

The Warmflow 2128 fault code means: your boiler's internal expansion vessel has lost its air pressure, which means it cannot safely manage the pressure changes in your heating system as it warms up.. It appears on 1 Warmflow 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: 12 Litre Pressure Vessel
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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Warmflow models that show the 2128 fault code

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

Source

Warmflow 2128 fault code information on this page is sourced and cross-checked against the official Warmflow service / installation manuals for each affected model.

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