High
31 on Johnson Starley C16d

Your boiler has lost its connection to the sensor that monitors air temperature, preventing it from heating 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

Duct air temperature sensor open circuit. Temperature sensor not connected or failed. Check wiring connections. Check sensor continuity.

From this model's manual
Verified against the Johnson Starley C16d installation & service manual, page 28.
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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