High
30 on Johnson Starley C26d

Your boiler has stopped working because it thinks the air in the heating ducts is overheating due to a faulty electrical sensor.

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 short circuit. Temperature sensor shorted to earth or failed. Check wiring and connections for shorting to earth. Check sensor resistance.

From this model's manual
Verified against the Johnson Starley C26d 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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