How much does it cost to fix Keston error code B 26?

Typical repair cost for the Keston B 26 fault is £80-150 including labour.

B 26 High

Keston B 26 Fault Code

Q: What does the Keston B 26 fault code mean?

Your boiler has stopped working because the water pressure inside the heating system has dropped too low to operate safely.

Also written as B26 — same fault.

The Keston B 26 fault code means: your boiler has stopped working because the water pressure inside the heating system has dropped too low to operate safely.. It appears on 3 Keston models in our database.

Technical description: Low water pressure

Typical repair cost £80-150 (including labour)

DIY fix possible

Locate the filling loop (usually a silver braided hose with one or two valves) underneath the boiler.Slowly open the valve(s) to allow cold mains water into the system while watching the pressure gauge.Stop when the needle reaches the green zone, typically between 1.0 and 1.5 bar, then ensure valves are fully closed.

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Keston models that show the B 26 fault code

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

Source

Keston B 26 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