How much does it cost to fix Keston error code B 28?

Typical repair cost for the Keston B 28 fault is £250-450 including labour.

B 28 High

Keston B 28 Fault Code

Q: What does the Keston B 28 fault code mean?

Your boiler has detected that the internal fan responsible for venting exhaust gases is not communicating with the system, so it has safely shut down to prevent unsafe operation.

Also written as B28 — same fault.

The Keston B 28 fault code means: your boiler has detected that the internal fan responsible for venting exhaust gases is not communicating with the system, so it has safely shut down to prevent unsafe operation.. It appears on 3 Keston models in our database.

Technical description: No signal from fan. Possible fan disconnected or faulty.

Typical repair cost £250-450 (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 28 fault code

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

Source

Keston B 28 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