High
Faulty PCB on Johnson Starley Aquair S 10

Your boiler's electronic brain is unable to send the correct signals to the fan, which prevents the system from starting up safely.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Call an engineer soon

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

What the manual says

Manufacturer manual

Measured DC voltage (0 to 10V) within Low Voltage fan connector (blue & yellow) is not greater than 2V, or error in sensor signal processing.

From this model's manual
Verified against the Johnson Starley Aquair S 10 installation & service manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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