How much does it cost to fix Keston error code bxx?

Typical repair cost for the Keston bxx fault is £150-350 including labour.

bxx High

Keston bxx Fault Code

Q: What does the Keston bxx fault code mean?

Your boiler has detected that the water inside the system has become dangerously hot or the water pressure is too low, causing it to shut down to prevent internal damage.

Also written as BXX — same fault.

The Keston bxx fault code means: your boiler has detected that the water inside the system has become dangerously hot or the water pressure is too low, causing it to shut down to prevent internal damage.. It appears on 1 Keston model in our database.

Technical description: Overheat or water pressure lockout (first digit displays 9, followed by flashing error code starting with b)

Typical repair cost £150-350 (including labour)

Engineer required

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

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Keston models that show the bxx fault code

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

C40 Repair: £150-350

Source

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

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026