How much does it cost to fix Keston error code B 19?

Typical repair cost for the Keston B 19 fault is £150-300 including labour.

B 19 High

Keston B 19 Fault Code

Q: What does the Keston B 19 fault code mean?

Your boiler has detected that the water returning to it has become dangerously hot, so it has safely shut down to prevent damage.

Also written as B19 — same fault.

The Keston B 19 fault code means: your boiler has detected that the water returning to it has become dangerously hot, so it has safely shut down to prevent damage.. It appears on 3 Keston models in our database.

Technical description: Return temperature exceeded 95oC

Typical repair cost £150-300 (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 B 19 fault code

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

C40 Repair: £150-300
C55 Repair: £150-300
C90 / C110 Repair: £150-350

Source

Keston B 19 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