2964 B High

Worcester Bosch 2964 B Fault Code

Also written as 2964B — same fault.

The Worcester Bosch 2964 B fault code means: your boiler has detected that water isn't moving through the main heating unit quickly enough, often caused by a blockage or a pump issue.. It appears on 3 Worcester Bosch models 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: Flow rate in heat exchanger is too low
Typical repair cost £150-£450 (including labour)

Engineer required

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

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Worcester Bosch models that show the 2964 B fault code

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

Source

Worcester Bosch 2964 B fault code information on this page is sourced and cross-checked against the official Worcester Bosch service / installation manuals for each affected model.

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