BoilerFaultCodes.com
b28 High Lockout

Your boiler has stopped working because the internal fan is not spinning correctly, meaning it cannot safely vent exhaust gases.

Call an engineer soon

Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description: No signal from fan

What causes this fault?

This fault occurs when the boiler's control board cannot detect any movement from the internal fan, which is essential for clearing dangerous exhaust fumes. The most common reason is a mechanical failure within the fan motor or a communication break in the electrical wiring connecting the fan to the main computer. In some cases, the fan may be physically blocked by debris or the control board itself may have stopped sending power to the component.

Typical repair cost £180-350 (including labour)

Engineer required

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

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